Set aside 100 g of tomatoes. Rinse 400 g tomatoes, crush and strain through a coarse sieve as desired. Season the puree with salt, white pepper and a few drops of Tabasco.
Soak the gelatin according to package directions, let it melt and stir into the tomato puree, as well as the yogurt. Let this mixture cool until it begins to gel. Whip the whipped cream until stiff and fold it in. Place the mousse in the refrigerator with the lid closed and set for at least three hours, preferably longer.
Season the juice of one lemon with salt, sugar and black pepper, add the oils to form. Finely grate the onion and add it. Rinse the basil, shake dry and set aside a few leaves. Cut the rest into tender strips and add to the salad dressing form.
Roast the seeds without fat in a small frying pan.
Rinse the lettuce leaves, e.g. head lettuce or oak leaf lettuce, drain well and spread evenly on four medium-sized plates. Drizzle over the basil salad dressing. Scoop dumplings of the tomato mousse with two spoons and place in the center of the lettuce leaves. Garnish with seeds, basil and tomato dumplings.
Tip: This recipe is excellent as a refreshing entrée.