Peel and wash the potatoes and cook in salted water for about 20 minutes
Wash and finely chop the basil, except for a little to garnish, and the parsley. Mix quark, mineral water, basil and half parsley. Season with salt and pepper
Peel and finely chop the onion. Wash and slice the tomatoes. Mix vinegar, salt, pepper and sugar. Beat 1/2 tsp. oil into the mixture. Mix with tomatoes and onion
Wash the fillet if necessary and dab dry. Fry in 1/2 teaspoon hot oil for 2-3 minutes on each side. Season with salt and pepper. Drain the potatoes. Arrange everything. Garnish with remaining basil and sprinkle with the remaining parsley.
You can also mix the marinade with a little broth instead of mineral water. It then tastes even spicier