Vareniki

Mix the flour, the egg, the warm water, the sunflower oil and the 5g of fine salt into a soft dough.

Knead for 8 minutes, until smooth and elastic and no longer sticking to your hands.

Wrap the dough and rest it for 30 minutes. Rolled straight away it fights back and shrinks the moment you lift the pin.

Boil the potatoes in salted water for 15-18 minutes, until a knife slides into a chunk and out again with no resistance at all.

Drain them and leave them in the hot dry pan for 2 minutes to steam off. Wet mash makes a wet filling, and a wet filling soaks through the dough and tears it as you seal.

Melt 50g of the butter in a frying pan over medium-low heat and add the chopped onions.

Cook the onions for 12-15 minutes, stirring now and then, until they are deep gold, soft and sweet.

Take the onions past pale and translucent. This is where the filling gets its flavour, and onions pulled off while still white leave you with plain mashed potato in pastry.

Mash the potatoes and beat in about two thirds of the onions with their butter, the 5g of fine salt and the ground peppercorns. Keep the rest of the onions for serving.

Spread the filling out on a plate and let it cool to room temperature. Warm filling steams the dough from the inside and slackens it while you are still shaping.

Roll the dough out to 2-3mm and cut 8cm rounds.

Put a heaped tablespoon of filling on each round.

Fold into a half-moon and press the edges firmly together, working from the middle outwards and pushing out the air.

Crimp the sealed edge by folding a rope of small pleats along it, or press it flat with a fork.

Lay them on a floured tray without letting them touch. You should get about 30.

Bring a large pan of water to a rolling boil and add the 20g of coarse salt.

Cook them in two batches so the pan is never crowded, stirring once as they go in.

Boil for 4-5 minutes after they rise to the surface, until the dough at the crimped edge is no longer chalky when you bite it. That doubled edge is the thickest part and the last to cook.

Lift them out with a slotted spoon, draining well.

Toss them with the remaining 30g of butter and the reserved fried onions.

Serve with smetana and the dill.