For the vinaigrette, dip the tomatoes briefly in boiling water until the skin is wrinkled. Then rinse with cold water and peel the tomatoes. Now core the tomatoes and cut into fine cubes. Also peel the onions and cut into fine cubes.
Mix the vinegar with the tomato paste, a little salt and pepper, the sugar and the olive oil. Season to taste and, if necessary, add seasoning. Put the tomatoes and the onion cubes in the vinaigrette and stir well.
For the carpaccio, peel and quarter the avocado and remove the stone. Wash the apple, quarter it and remove the stone. Then cut both into thin slices. If necessary, briefly drizzle the apple with lemon juice so that it does not turn brown. Arrange the slices alternately on a plate. Add the crayfish and drizzle with the vinaigrette.