Potato zrazy with mushroom filling (Kartofelnye zrazy s gribami)

1. Peel the potatoes, cut them into chunks, boil in salted water until tender, drain thoroughly and mash while still warm; leave to cool until lukewarm so the mash isn't sticky.

2. Meanwhile finely chop the onion and soften it in the butter until translucent; add the chopped mushrooms and fry until all their liquid has evaporated and they are nicely browned; season with salt and pepper, then let cool.

3. Add the egg and flour to the lukewarm mash and knead quickly, just until you have a smooth, shapeable dough; if it's very soft, add another spoonful of flour.

4. With wet hands, shape the dough into 8 equal balls, press each into a flat disc on your palm, put a heaped spoonful of mushroom filling in the middle, fold the edges over and shape into an oval, slightly flattened croquette.

5. Roll the zrazy in breadcrumbs and fry in the hot oil over medium heat for 3-4 minutes per side until golden brown; drain on kitchen paper.

6. Serve hot with plenty of sour cream and a sprinkling of fresh dill, with pickles or a fresh salad on the side.

Tip: The secret of the dough is dry potatoes: after draining, put them back in the hot pan for a few minutes so the remaining steam evaporates – you'll need less flour and the zrazy stay soft inside.