Put the beef, vegetables, celery leaves, bay leaf, allspice and peppercorns in a deep, heavy-based pan with a lid and pour over water to cover by 2cm (¾in). Bring to a boil, reduce the heat, then cover with the lid and simmer gently for 4–5 hours, or until the meat is falling away from the bone.

To make the dough, put the flour in a large bowl and combine with the other ingredients using your hand. Bring the ingredients together into a dough ball, then turn out onto a floured work surface and knead for 6–7 minutes. Cover with a clean, damp dish towel and allow to rest for 20–30 minutes.

To make the filling, use a sieve to remove the meat and vegetables from the broth and set aside. Season the broth with salt, white and black pepper and dill, to taste. Keep warm and set aside.

Take the meat off the bone (discard the bones). Put the meat, the carrots, parsnip, leek and cabbage in a food processor and whizz to a paste (discard the remaining sieved ingredients from the pan). Season the filling mixture well with the mustard, salt and white and black pepper.

Roll the dough out as thinly as possible (about 0.5mm) and cut the dough into squares of about 9–10cm (3½–4in). Place a heaped teaspoon of filling in the middle of each. To make Rectangle style pierożki, pinch the square in the middle, while holding together the top and bottom edges, press down hard to seal along the middle, so that you get a rectangle shape. While firmly holding at one end of the crease along the middle, use your thumb and forefinger to push the bottom of the dumplings up towards where you are holding it, then seal the two open corners. Repeat on the other side.

Bring a large pan of salted water to the boil and cook the pierożki in batches. Once they float to the top, give them an extra minute, then remove with a slotted spoon, shaking off any excess water.

Meanwhile, prepare the bowls, ladling broth into each one. Serve the pierożki straight in the bowls with the broth and sprinkle with dill. The next day, if there are any leftover pierożki, fry them in butter for a crispy version.