Peel the vegetable onions and cut into fine rings. Separate eggs and mix egg yolk with milk. Season with 1 pinch of salt, sieve 100 g flour on top and mix to a smooth dough. Beat the egg whites with the whisks of the hand mixer until stiff and fold into the dough. Slowly heat the oil in a tall pot.
Put 2 tablespoons of flour on a plate. Turn the onion rings in it, pull them through the pastry and fry them in the oil until golden brown, turning them once. Put onion rings on kitchen paper and season with 1 pinch of salt. Mix sour cream, lemon juice, salt, pepper and 1 pinch of sugar in a bowl. Wash and roughly chop the parsley and fold into the sour cream