Mince meat along with fat and onion, season with salt and mix well. Knead elastic dough, like for pelmeni or ravioli. Divide the dough into equal pieces, roll them out into an oval, put the filling and pinch. Cook byoriki in salted water, like pelmeni or ravioli. Serve them poured over with melted butter. You can also serve with sour cream or some kind of sauce.