Peel the potatoes, cut into slices, boil until ready in salted water. Drain, add egg and butter, and mash.
Chop the onion finely. Wash the mushrooms and cut into small cubes or cubes. First, fry a little onion, then add the mushrooms, salt and fry until tender.
Move the mushrooms into a colander, let the liquid drain.
With 1 tablespoon of previously cooked mashed potatoes, form a tortilla. In the middle, put a serving of mushrooms. Wrap the filling in the potato to form a “patty”.
Roll potato zrazy with mushrooms in flour. Cook over medium heat until golden brown.