Clean and wash the peppers. Cut 1/4 each into very fine strips, the rest into thick strips. Clean and wash the cucumber and cut about 1/3 into thin slices. Cut the rest into thick sticks. Peel onions. Cut 1 into fine rings, dice 1 finely. Wash tomatoes and cut into thin slices. Clean, wash and dry lettuce leaves
Knead onion cubes, mince, salt and pepper. Form 4 flat minced steaks. Fry in hot oil in a coated pan for approx. 3 minutes on each side
Cut the buns in half. Spread the lower halves with 1/2 tsp. mustard on each. Cover with lettuce, onion rings, tomato and cucumber slices, fine strips of paprika and one minced steak each. Add 1 teaspoon each of ketchup and quark. Place the upper halves of the rolls on top. Arrange burgers and vegetable sticks. Add the remaining quark for dipping