Clean, wash and cut the peppers into small cubes. Clean and wash salads. Pluck frisée and endive into bite-sized pieces. Mix vinegar and mustard. Season with salt, pepper and sugar.
Fold in 3 tablespoons of oil. Season again and mix with the salad ingredients. Peel onions and cut into rings. Then turn them in flour and tap them a little bit. Wash the steaks and pat dry.
Cut the fat edges at intervals. Heat 2-3 tablespoons of oil. Fry the steaks for 4-5 minutes on each side. Season with salt and pepper. Heat the frying fat as well. Fry the onion rings for about 3 minutes until golden brown.
Serve steaks sprinkled with onion rings and chopped parsley. Serve with salad.