Clean, wash and chop the soup greens. Peel onion and garlic and chop finely. Clean, wash and, except for one, roughly dice the tomatoes. Heat the fat. Brown the soup greens, onion and garlic in it.
Add the tomatoes. Deglaze with 3/4 litres of water and bring to the boil. Stir in stock. Add herbs. Let simmer for about 1 hour. Wash basil, dab dry and cut into strips, except for something to garnish.
Pass the stock through a sieve, bring to the boil and season with salt and pepper. Add basil strips. Quarter the remaining tomato, remove seeds and cut into strips. Warm the tomato strips in the soup.
Arrange the soup in preheated plates. Place 1 tablespoon of mascarpone on each plate and sprinkle with pepper. Serve garnished with basil.