Cut the onion into fine cubes. Wash the fresh tomatoes and cut them into large pieces. The flower does not have to be cut out as the soup will be passed through later. Cut the basil into strips.
Sweat the onions with the olive oil, add the tomatoes, sweat through. Add the water until the tomatoes are covered. Season with salt, sugar and pepper (white) and cook well. Puree with a magic wand. Pass with the help of a sieve