Wash the tomatoes, remove the stalk and cut into small pieces, except for 1 tomato. Peel and chop the onions. Wash basil, shake dry. Heat 1 tablespoon of oil in a saucepan. Sauté onions for 1-2 minutes, then stir in tomato paste. Add tomato pieces and 2 basil stems. Fill up with 800 ml water. Season with salt and pepper. Let the soup simmer at low heat for about 30 minutes
Cut 1 tomato into quarters and remove seeds. Cut the flesh into small cubes. Pass the soup through a sieve into a pot. Add the tomato pieces to the soup, bring to the boil, season with salt, pepper and possibly some sugar
Grate cheese. Heat the tortilla slightly in a pan or microwave and sprinkle with cheese. Roll up the tortilla and cut into snails. Heat 1 tsp. oil in a coated pan. Fry the tortilla snails for 2-3 minutes, turning them over
Arrange soup and tortilla snails in deep plates and garnish with basil leaves