Has there ever been an encirclement without superior numbers or mobility

History is FULL of examples of a numerically smaller force encircling a numerically larger one.

Encirclement is one of the most effective ways to achieve a battlefield victory.

Encirclement puts the encircled at a tremendous disadvantage.

1. restricts the movement of the encircled
2. cuts the encircled from their lines of communication (and supplies)
3. causes great psychological distress among the encircled troops
4. distressed and panicked troops often did irrational things

In fact the whole concept of Blitzkrieg was based on fast breakthrough, deep penetration, and envelopment.

What the Germans didn't know was the Mongols actually did one better. The only thing better than total encirclement was, an INCOMPLETE total encirclement. In this case the encircling forces have the means to fully encircle the victims, but choose not to. This entices the encircled forces to panic and make a break for it from a corridor deliberately left open by the enveloping forces. Trying to escape from a collapsing pocket with a disintegrated command and control is quite possibly the most dangerous situation for an army.

Let's look at a few super famous examples.

The battle of Teutoburg Forest In this battle, numerically inferior Germanic forces encircled and annihilated 3 roman legions. The Romans were lured into Teutoburg Forest where they were cut off and then whittled down by a series of ambushes.

Battle of Tannenberg The German Empire won a major victory against a numerically superior Russian army. In this battle, the Germans learned of the russian plan via unencrypted wireless communications. They let the russian push forward into a trap where upon german reinforcements fell on their rear an encircled them.

The battle of Ulm was a beautiful battle of the War of the Third Coalition. Technically, Napoleon had overwhelming local numeric superiority. But he achieved it by striking before his massively larger foes could gather their forces.

But to me, the absolutely weirdest encirclement battle was the Battle of Alesia where Julius Caesar built the famous double wall encirclement. He encircled his Gallic foes at Alesia. But his enemies had strong walls. So he built another set of walls around Alesia. Then the Gallic forces rallied to relief Alesia. Caesar built another set of walls outside his first wall to fend off the reinforcement. So the Romans had numeric superiority against the forces defending Alesia. But the Gallic relief force had numeric superiority on the Romans, who were themselves encircled. Spoiler alert, the Romans won.

Except for Ulm, mobility didn't even come into play. Teutoburg was won by the clever use of terrain. Tannenberg was won by the clever use of information, and letting the enemy encircle themselves. Alesia was a fine example superior siege engineering.

Without superior numbers, the most famous example which I know of is the Battle of Cannae. 50,000 Carthaginians under the great general Hannibal encircled 86,400 Romans soldiers and their allies. The Greek historian Polybius reports the Romans and their allies died almost to the last man, (85,630 killed on the Roman side, vs 5,700 killed on the Carthaginian side). The tactic of encircling an army comprising a superior number of soldiers lead to one of Romes greatest defeats, and marked the Carthaginian General who conceived and executed the maneuver one of histories greatest generals.

Hannibal intended that his cavalry, comprising mainly medium Hispanic cavalry and Numidian light horse, and positioned on the flanks, would defeat the weaker Roman cavalry and swing around to attack the Roman infantry from the rear as it pressed upon Hannibal's weakened center.[49] His veteran African troops would then press in from the flanks at the crucial moment, and encircle the overextended Romans.
....
Soon they were compacted together so closely that they had little space to wield their weapons. In pressing so far forward in their desire to destroy the retreating and seemingly collapsing line of Hispanic and Gallic troops, the Romans had ignored (possibly due to the dust) the African troops that stood uncommitted on the projecting ends of this now-reversed crescent.[52] This also gave the Carthaginian cavalry time to drive the Roman cavalry off on both flanks and attack the Roman center in the rear. The Roman infantry, now stripped of protection on both its flanks, formed a wedge that drove deeper and deeper into the Carthaginian semicircle, driving itself into an alley formed by the African infantry on the wings.[60] At this decisive point, Hannibal ordered his African infantry to turn inwards and advance against the Roman flanks, creating an encirclement in one of the earliest known examples of a pincer movement.

Sources:

• Polybius
• The Battle of Cannae

Fraustadt, 1706 was a classic double envelopment.

Trapped by Swedish cavalry to their front and infantry to their rear, the defeated Saxon-Russian forces surrendered en masse.

Swedes            Saxons & Russians
9,400             20,000
452 killed        7,377 killed
1,077 wounded     7,300–7,900 captured

Narva, 1700 was a "double double envelopment" (both sides of the Russian line were enveloped separately).

the Swedes moved to the south and north along the fortification line, rolling up the Russian defense. They attacked inexperienced Russian regiments and crumbled them one by one. There was panic and chaos, Russian soldiers began killing foreign officers and de Croy with his staff hurried to surrender. Masses of panicking Russians troops rushed to the only Kamperholm Bridge over the Narova River, located at the northern edge of the defensive line. At one crucial point, the bridge collapsed under retreating Russian troops.

Swedes             Russians
10,500 men         37,000 men
667 killed         around 6,000–8,000 killed, wounded and drowned
1,247 wounded      total losses up to 18,000   

("Swedes" means mainly Swedes and Finns.)

Battles during Winter War, between Finland and the Soviet Union have many examples of encirclements done by finlands against soviets. For example, Battle of Suomussalmi or Battle of Raate Road.
One might say that finnish forces had more mobility, which is true, but the really important factor was the encirclement, because soviet forces where reduced to small pockets, which were destroyed one by one, because finnish did not have enough strenght to destroy all of them at the same time.