Were there luxury restaurants in East Germany?

Yes, there was 'luxury' in gastronomical areas in East-Germany.

This yes comes with a slight caveat: that was more rare than in the West and also in a 'reduced amount', often catering to international guests spending hard currencies, or rewarding loyal workers and party members, with ordinary workers very seldom enjoying the offerings, which were subsidised for them, but still expensive, despite the restaurants probably still not always sorted into the same categories like for example top-notch 'French cuisine' ones in the West of that time.

On top of the East-Berlin TV-tower there was a 'Telecafé', a rotating platform for viewing Berlin: coffee was served, very limited food offerings (menu, from 1976), the queues were usually gigantic, and after a full rotation completed in 60 minutes all places had to be evacuated, swiftly. Offerings probably wouldn't count as anything luxurious for the western palate. For Easterners things might be remembered slightly differently, as the otherwise still prestigious place always had 'real coffee'; compare 1977 East German coffee crisis.

Most of the food hospitality in the GDR's 26000 restaurants (33000 including pubs with food) during the 1980s was indeed quite simple and that showed already in the cutlery: aluminium was standard, stainless steel was seen as higher end.

Local and seasonal food in traditional dishes might have been quite good, and very affordable, but more 'international' appeal often required the usage of canned food and otherwise rare ingredients that were many times just 'unavailable'. Or a lot of fantasy and creativity. The latter often covered up by sneakily exchanging true specialities of decent quality like 'dark brewed beer' without any warning with 'coloured light beer'.

— "DDR-Gastronomie: Bienen vom Grill", 21.11.1982, Der Spiegel 47/1982. A news magazine article reporting on a West-German food critic writing his version of a 'Guide Michelin for East Germany' and coming up with 55 very good restaurants and "1500 recommendations", mostly on local specialities… A verdict many Eastern chefs proudly enjoyed (the highlight in the article's title details the jokingly offered 'Japanese specialty of grilled bees' one chef would have served the critic if only he knew that a Westerner would come and wanted to really taste the best that was on offer… ;) while the official bureaucrats regarded this pamphlet as nothing but an insult. Compare the above to the reaction the GDR publishers put out with

There were many elegant restaurants in the GDR by the 1980s, and some attention was now given to local specialties and historic atmosphere. Manfred Otto’s Gastronomische Entdeckungen in der DDR, published in 1984, listed 100 restaurants and offered recipes from each of them. The book was organized by historic region rather than—as in the more down-market Restaurants und Gastätten der DDR—by administrative district (Bezirk). Gastronomische Entdeckungen seems to have been directed to foreign (i.e., West German) tourists, however. Even if almost anything was available for a price by the 1980s, it is not clear which GDR citizens could afford it.

— Freedman 2013, link added, see ref below, and cf. Küche der Deutschen Demokratischen Republik (East German Cuisine)

Things even Westerners would consider upper class were usually restricted to said Westerners in things like an

Interhotel was an East German chain of luxury hotels. It was founded in 1965 as a chain.

These were catering to an international audience with a clear focus on Western palates, and Western money.

But when Honecker took over in 1971 his New Socialism or "Einheit von Wirtschafts- und Sozialpolitik" ~ 'Unity of Economic and Social Policy' included 'more spending for the workers' and meant that indeed 80% of the rooms were reserved not for non-socialist foreign guests, but loyal FDGB members at heavily subsidised prices. Restaurants serving local communities were usually required to serve at fixed prices and include at least one complete meal at the 'affordable for everyone' 'price index level 2'. Price index levels ranged from the lowest 'class 1' to the highest 'class 5', with the rare possibility of an extra 'class S', there with even 50% surcharge on the maximum price allowed.

Some examples of menus from back then here, with the first object emphasising the local tradition, with fairy tale theme, and indication of the standard 'price level III' and for comparison the price 'level S' in the most prestigious Palace of the Republic with its offering for the last Sylvester/New Year's Eve evening menu 1989:

You might also compare the special occasion menu from 1989 above with a very much more conservative listing in the once 'biggest gastronomy project complex in the whole of the GDR' in Dresden for the same occasion in 1981, where we can discern one method of differentiating price levels from III to S1, merely portion size:

A small but colourful collection of the gamut of GDR menus over the years is depicted here. Note that even the otherwise robust and lowly worker's pub of price level 2 in Leipzig offered the extraordinary & quite expensive little caviar dish, or how the cruise ship menu from 1988 offered things like kangaroo-tail meat, a really rare 'catch' in East-German fields, woods and forests.

Not just to reward them, but also to show western guests that indeed 'ordinary' East-German workers were able to enjoy 'real luxury' in 'real socialism'. Certainly not always, but also certainly way too often heard and remembered, the menus almost always continued to look very impressive, only when guests then ordered their choice exactly that choice was 'just went out, sorry'. The grain of salt to take with these stories is of course that these things happened all the time, more often in the East than in the West, but that in the East with its more limited choices and changing scarcities still nobody was sent home hungry, once seated, and that the 'upper class' venues changed their menus often enough to react somewhat more flexibly to patrons' choices in light of those suppliy issues that crept up on them occasionally.

These restaurants were also open to non-hotel guests, albeit queueing for these places atthe table in the then quite expensive dining halls was the usual nightmare. And the offerings were still somewhat 'provincial' during the 1970s:

The 'International' in Dresden had 1974 the following menu:

Hackbraten mit Letscho und Pommes Frites — 3,80 M
Rostbratwurst mit Sauerkraut und Kartoffeln — 3,45 M
Sauerbraten mit Klößen und Paprikasalat — 4,85 M
Kaninchenpfeffer mit Pommes Frites, Apfelmus — 4,00 M
Hühnerfrikassee m. Risotto, Blumenkohl u. Fleurons — 4,80 M
Ente ausgelöst, gebackene Früchte, Pommes Frites — 5,90 M
Warme Küche v. 15–17 Uhr geschlossen

That first item is: meat loaf with lecsó and French fries… And do not expect to be served warm meals between three and five.
But meals improved later.

But the Neptun was pure luxury. Built by Sweden for foreign currency, it was originally intended to be a hotel for foreigners only, or so Ulbricht had thought. The best waiters and cooks had been prepared there "for the absolute luxury show" for guests from the "non-socialist currency area". And then this: in September 1971, the Politburo announced that the most beautiful hotels in the Republic would be handed over to the FDGB for use.

One of the great gestures of the patron Erich Honecker, downright revolutionary: the proletarians in the luxury hotel! Honecker must have felt as he did in heroic times when it was rumoured that houses of worship were being converted into horse stables under the Soviet star! In the Neptun, now owned by the people, eighty per cent of the guests were FDGB holidaymakers and twenty per cent foreign currency guests from capitalist countries - the tennis players in their Lacoste shirts could see that the little people in the workers' and peasants' state lived like princes. […]

Mr. W., the hotel manager, adjusted to the changed circumstances and now took on nothing more ambitious than to prove that service is possible, even in a hotel that is mainly used by ordinary people. He wanted to teach the working class the culture of eating, to open up the enjoyment of service to them. He kept his HO waiters - unusual enough in the gastronomic lottery economy - firmly in check between control and reward. He abolished the still common division between black and white, between waiter and cook, confectioner and server. He sent the cooks to the restaurant, the ice cream confectioners were allowed to bring their sundaes to the tables personally.

W. demonstrated to his guests what it meant to eat healthily, had the chambermaids put toothbrushes in their bathrooms in case one of them, for whatever reason, had not brought one. And he forbade them to shuffle through the hotel lobby in their bathrobes and slippers.

— Jutta Voigt: "Der Geschmack des Ostens. Vom Essen, Trinken und Leben in der DDR", Aufbau Verlag, Berlin 2017. (translated)

The Hotel Neptun in Warnemünde showcases that these higher end gastro-services were not purely concentrated to the socialist 'shopwindow of East-Berlin' or the somewhat equally international Trade Fair city of Leipzig, but to be found in smaller cities as well, often tourist destinations, nationally as well as internationally, not just administrative centers.

These tendencies were certainly not widespread in the early years, but came to some fruition in the 1970s and eighties:

Two aspects of privileged dining in the German Democratic Republic (GDR) during the 1970s and 1980s are discussed in this essay: state dinners given for visiting foreign dignitaries and meals served on vacation cruise ships run by the Freier Deutscher Gewerkschaftsbund (FDGB), the umbrella union organization. The guests at the official occasions were members of the ruling elite, but their experience of gastronomic luxury was similar to that of the guests on the cruise vessels. In fact, such boat trips represented a modest but significant level of social distinction. What was served to the fortunate workers and other loyalists picked for these voyages resembled the selections that were presented to foreign leaders as exemplary of the culinary ambitions of the GDR. Despite the notorious shortages and food supply problems of East Germany, there was a general aspiration for gracious, varied, and interesting dining. This was reflected in the growth of restaurants and in the changes in recipes proposed to the majority of East Germans, who usually cooked at home. […]

After the 1950s there was a more than adequate supply in general, but food remained hard to acquire and often of poor quality, while service in stores and restaurants was, for the most part, dreadful. Basic items such as butter or sugar were in constant danger of disappearing and so were hoarded. There were periodic crises like the sausage shortage of 1963, the unavailability of coffee in 1977, and butter and cheese problems in the fall of 1982. Except for apples and red cabbage, fresh produce was difficult to buy in decent condition because the transport and storage systems could not effectively handle perishable goods. As Jutta Voigt wryly notes in her memoir Der Geschmack des Ostens (The Taste of the East), fruit and vegetables were, in effect, “class enemies” that “sabotaged the building of socialism as much as they could.” […]

By the 1980s distinctions based on access to hard currency were obvious, unavoidable, and resented by those consequently shut off from the enjoyment of even minor indulgences. At a luxurious but officially egalitarian French restaurant located within the Palace of the Republic complex, the seat of the GDR parliament, East German currency was usually accepted, but even here special offerings such as the “Pfeffersteak à la Toulouse-Lautrec,” flambéed in Calvados, had to be paid for with West German marks. At issue in this instance was the expense of the imported Calvados. […]

The 1970s and 1980s witnessed a turn toward a more eclectic and international style, something that did not happen in the USSR: Arab, Cuban, and Vietnamese recipes proliferated—thanks, in part, to the influx of migrants from allied Socialist states. Curry, pizza, and fondue were popular, a delayed response to their diffusion throughout Western Europe.

Authenticity was not vitally important:

“Soy sauce? No problem! Erwa-Speisewürze tastes the same: you only need faith.”

A 1979 menu from the main restaurant of the Palace of the Republic featured nasi goreng, an Indonesian rice dish.18 On the inserted menu of the day (Tageskarte) for the week of 13–19 February 1979 was an intimidating Double Rumpsteak Mexican Style (for two persons), accompanied by pepper strips, tomatoes, pickles, artichoke hearts, beef marrow, and peas, all in a potato nest, along with anchovy butter and French-fried potatoes. Slightly more convincing Mexican cuisine was available at places like the Tampico, a restaurant in the Chemnitzer Hof Hotel, where an undated menu (likely from the 1980s) included chili con carne and the “Tampico Mixed Grill” with tortillas. […]

Notwithstanding rising living standards or anxiety over the rapid growth of the Federal Republic’s consumer culture, there was no strongly expressed “culture of gourmandise”; […]

Official dinners, which usually consisted of four courses, displayed a cau- tious sophistication, something between ordinary East German specialties and international taste. The menus of the cruise ships, like those of the nicer resort hotels in East Germany, included the best that was available to persons of mod- est but temporarily privileged status. These two types of menus represented different forms of elite dining, but, as indicated, the offerings were very similar. […]

The menus for the dinners at the Palais followed an unwavering order of hors d’oeuvre, soup, main course, and dessert. The hors d’oeuvre was accompanied by vodka (usually from the East German town Wilthen) or Nordhäuser “Feiner alter Korn,” a schnapps whose origins go back to the early sixteenth century. The wines were most often from the two small recognized East German wine regions: Saale-Unstrut and the tiny Saxon terroir on the Elbe near Meissen and Dresden. The ability to enjoy these was itself a mark of substantial distinction because their exiguous production made them virtually unknown to ordinary East German citizens. Dessert was occasionally accompanied by sparkling wine (Sekt) from Freyburg, often of the Rotkäppchen label, a celebratory beverage whose resurgent popularity since unification has practically effaced its former reputation as a symbol of the GDR’s gustatory mediocrity. Brandy (usually from Wilthen as well) was served with coffee after the meal.

— Paul Freedman: "Luxury Dining in the Later Years of the German Democratic Republic", in: Mary Fulbrook & Andrew I. Port (eds): "Becoming East German. Socialist Structures and Sensibilities after Hitler", Berghahn Books: New York, Oxford, 2013. worldcat