Ukrainian
Fry the onion in 2 tbsp of the oil over medium heat for 5 minutes, add the mushrooms and cook for 15 minutes until their liquid evaporates; stir in the garlic, 3 g of salt and a pinch of pepper and let it cool.
Cut the pork across the grain into 8 slices about 1.5 cm thick, cover with plastic wrap and pound them to 4-5 mm.
Season the slices with the remaining salt and pepper, spread an eighth of the mushroom filling (about 3 tbsp) on each and roll them up tightly, securing with toothpicks or kitchen twine.
Dust the rolls with the flour and brown them on all sides in the remaining oil in a deep pan or casserole, about 6-8 minutes.
Whisk the sour cream with the water, pour it over the rolls, cover and braise over low heat for 40 minutes, turning once.
Uncover for the last 5-10 minutes if the sauce is thin, until it coats a spoon.
Remove the toothpicks or twine and serve 2 rolls per person with the sauce, sprinkled with dill, alongside mashed potatoes or buckwheat.