Upvote:1
There is an Indonesian sauce called kecap manis that sounds exactly the way you describe. It is also common outside of Indonesia, including China and South East Asia.
That may not be what you had. If it was very sticky, the here in Ecuador they call it Eel Sauce which is mostly soy sauce with lots and lots of sugar. Another possibility is a variant on Hoisin sauce which has a more beany taste but is usually more brown rather than almost black like the one you show.
Upvote:4
It could be 甜面酱/甜酱 or sweet bean sauce aka sweet flour sauce or just sweet sauce. You can probably find it in a Chinese supermarket under one of those names.