Chop finely . Melted in the butter and fry the onion in it until shimmering. Sprinkle the flour and stir until golden brown. Add the cream, stirring to make a smooth mixture. Reduce the heat and leave to thicken. Season with pepper and salt to taste. Remove from heat and set aside. Sauerkraut is washed and cut into very thin strips. Cummin beat mechanically in a mortar and add to cabbage along with the sauce. Peel the potatoes and cut into cubes of about 1 cm. Blanching is 3 minutes in salted boiling water, drain and mix with cabbage. Egg whites are broken down into the snow with a pinch of salt and add to the cabbage. Insert the parsley. Crisp is smeared with butter and dusted with bread crumbs. Cabbage mixture is poured into it and bake in a preheated oven, 170 C, 40 minutes. Meanwhile, wash Lime (lemon) with hot water, grate the rind finely, squeeze the juice of half fruit Both are mixed with crème fraîche (drained yogurt). Serve garnished with the sauce. Go to steaks or fillets, going for warm appetizer.