How to cook pelmeni in the microwave?
Anything that is normally cooked by simmering / boiling in liquid can be cooked in a microwave in the same way, if your microwave can keep the liquid simmering.

So for pelmeni just put them in a bowl of salted boiling water (use a kettle or the microwave to bring it to the boil first), bring back to a simmer and cook on high for the same length of time you'd cook them in a pan on the stove. If your microwave is not powerful enough to keep the water simmering, cook smaller amounts at a time.

It's less efficient than doing it on the stove, takes more time and is more fuss. The pelmeni will take longer to come back to a simmer than they would on the stove, so the dough will be relatively overcooked and soft.