Potato dumplings with mushroom sauce (Kopytka z sosem grzybowym)

1. Soak the dried porcini in 150 ml of hot water. Boil the potatoes in their skins in salted water until tender, peel while still warm, mash and let them cool completely.

2. Add the egg, a teaspoon of salt and enough flour to the cooled potatoes to make a soft but not sticky dough; don't overwork it, or the kopytka will turn tough.

3. On a floured board roll the dough into finger-thick ropes, flatten them slightly and cut diagonally into 2 cm pieces – their shape gives them the name "little hooves" (kopytka).

4. Meanwhile soften the finely chopped onion in the butter until translucent, add the sliced mushrooms and the chopped porcini and fry for 8 minutes; pour in the strained porcini soaking liquid and simmer for 5 minutes.

5. Take off the heat, stir in the sour cream, season with salt and pepper and warm through over low heat without boiling. Cook the kopytka in plenty of boiling salted water, for 2 minutes after they float to the surface.

6. Lift them out with a slotted spoon, toss with the mushroom sauce and serve sprinkled with chopped parsley.

Tip: Kopytka are the "gnocchi" of Polish cooking; always let the potatoes cool completely, otherwise they need lots of flour and the dumplings turn gluey.