Mix yoghurt with vinegar. Season to taste with salt, pepper and sugar. Clean and wash the salad and pluck into bite-sized pieces. Wash the cucumber, cut or slice thinly. Clean, wash and slice radishes.
Wash the sprouts and let them drip off. Knead minced meat with onion soup powder and egg. Shape into balls. Heat oil in a frying pan and fry the balls for 6-8 minutes. Arrange lettuce, cucumber and radishes on plates.
Drizzle with yoghurt sauce. Spread balls on top. Sprinkle with sprouts. Serve with toasted white bread.