For the mushroom and sauerkraut filling
- 50g/2oz dried mushrooms
- 250g/9oz ready-made sauerkraut (available in jars from larger supermarkets)
- 40g/1½oz butter
For the cottage cheese and potato filling
- 250g/9oz floury potatoes, such as Maris Piper, cut into pieces
- 3 tbsp olive oil
- 1 medium onion, finely diced
- 250g/9oz half-fat cottage cheese
For the dumpling dough
- 250g/9oz self-raising flour, plus extra for dusting
- 1 tsp salt
- 1 tbsp vegetable oil
- 150ml/5fl oz warm water
For the mushroom and sauerkraut filling, soak the dried mushrooms in 300ml/10½fl oz water and set aside to infuse for 1 hour.
Drain the sauerkraut in a colander and rinse under a tap to remove some of the acidity. Transfer to a pan of boiling water. Reduce the heat until the water is simmering and cook the sauerkraut for 30 minutes. Drain well.
Remove the mushrooms from the water using a slotted spoon, reserving the water. Finely chop the mushrooms.
Heat the butter in a frying pan over a medium heat. Add the sauerkraut, mushrooms and the reserved water. Bring the mixture to the boil. Continue to boil the mixture until all of the liquid has evaporated, then remove from the heat and set aside until cool.
For the cottage cheese and potato filling, boil the potatoes in a pan of salted water until soft enough to mash (about 20 minutes). Drain well and set aside to cool.
Heat the oil in a frying pan over a medium heat and fry the onions for 4-5 minutes, or until crisp and browned. Reserve a tablespoonful of the onions for the garnish.
For the dumpling dough, sift the flour into a large mixing bowl and make a well in the centre. Fill the well with the salt, oil and water. Using your fingers, gradually stir the flour into the wet ingredients, until the mixture comes together as a soft dough.
Turn the dough out onto a lightly floured work surface and knead for 5-8 minutes, or until it is smooth and glossy. Wrap the dough in a clean tea towel and set aside to rest in a cool room for at least 20 minutes.
When the potatoes have cooled, transfer them to a large bowl and crumble over the cottage cheese. Mash until smooth, then stir in the fried onions until well combined. Set aside.
To shape the pierogi, roll out the dough onto a lightly floured surface to a thickness of 3mm. Cut 10cm/4in rounds from it using a pastry cutter.
Place one teaspoonful of the cottage cheese and potato filling into half of the pastry rounds, and one teaspoonsful of the mushroom and sauerkraut filling into the remaining pastry rounds. Brush a little water around the edge of each pastry round, then fold the edges together to create a bulging semi-circular dumpling, pressing the edges together to seal.
Poach the pierogi, in batches if necessary, in a deep-sided pan of boiling water for 3-4 minutes, or until they float to the surface.
To serve, pile the pierogi onto serving plates and serve the soured cream in small bowls alongside. Sprinkle with the reserved fried onions and the dill.