Peel the onion and cut into fine cubes. Clean and wash the zucchini and tomatoes, except for a few panicles for garnishing. Wash aubergines as well. Halve the zucchini lengthwise and cut them diagonally into pieces. Cut tomatoes and eggplants in half. Crush garlic with the ball of your hand.
Put vegetables, onion and garlic in 4 portions on aluminium foil. Season with salt and pepper and drizzle with olive oil. Fold over the tin foil and close at the sides. Place on the grill and cook for about 15 minutes. Fry sausage snails on the grill for 3-5 minutes while turning. Arrange vegetables and sausage snails on plates and garnish with nasturtium blossoms