Wash the zucchini, pat dry, cut off the ends just short, cut in half lengthways and scoop out with a teaspoon. Finely chop the scraped pulp.
Peel onion and garlic and chop finely. Peel and core the tomatoes, chop the flesh
Heat 2 tablespoons of oil in a pan, fry the onion + garlic until translucent, add the zucchini and tomato pulp, lightly salt. Add the herbs, sugar and vinegar and stew everything on a low heat for 20 minutes. Season the mixture well with salt and pepper and pour into the zucchini halves. Preheat the oven to 200 ° C.
Place the filled zucchini on a greased baking sheet, sprinkle with parmesan and the remaining oil, bake for 20-30.