Soak rolls in cold water. Wash and clean the zucchini and tomatoes. Halve the zucchini, quarter lengthwise and cut into 1 cm thick pieces. Cut the tomatoes into pieces. Peel and finely chop the onion.
Squeeze the buns. Knead minced meat, bread roll, half onion and egg. Season with salt and pepper. Form 8 flat meatballs from the minced meat mixture. Roast the pine nuts in a pan without fat, take them out.
Cut mozzarella into 8 slices. Heat 2 tablespoons of oil in a frying pan, fry the meatballs for 8-10 minutes over medium heat, turning them over, and cover with cheese. Cover and fry until the cheese has melted.
Heat 1 tablespoon of oil in a second pan and sauté the remaining onion cubes in it. Fry the prepared vegetables for about 5 minutes, turning them over. Pluck the basil and thyme from the stalks and chop them, except for a little to garnish.
Stir vinegar into the vegetables and season with salt, pepper, sugar and herbs. Bring to the boil and simmer for about 5 minutes. Arrange tomato-zucchini vegetables with meatballs, sprinkle with pine nuts and garnish with thyme and basil.