Peel and wash the potatoes and cook in salted water for about 20 minutes. In the meantime, wash the salad and shake dry. For the vinaigrette, mix 2 tablespoons of vinegar, mustard, salt, pepper and 1⁄2 tsp. sugar. Fold in 2 tbsp. oil.
For the fried onions, peel the onions and cut them into fine rings. Heat 1 tablespoon of oil in a frying pan. Brown the onions in it thoroughly. Sprinkle 2 tsp. sugar over them and caramelise. Deglaze with 3 tbsp vinegar. Keep warm.
For the steaks dab meat dry. Season with salt and pepper. Whisk the eggs in a deep plate. Turn the steaks one after the other in flour, egg and breadcrumbs. Heat 3 tablespoons of oil in a frying pan. Fry the steaks in it in portions on each side for about 2 minutes.
For the puree, drain the potatoes. Add milk and butter and mash everything finely. Season to taste with salt and nutmeg. Arrange everything.