Put the couscous in a large bowl. Pour 75 ml boiling salted water over it and let it stand for about 5 minutes. Loosen up with a fork and let cool down
Meanwhile, wash the tomatoes. Cut off approx. 1/5 of the tomatoes at the base of the stalk as a "lid". Hollow out the tomatoes. Chop the inside of the tomatoes (approx. 100 g). Wash and clean the zucchini and cut into small cubes. Peel and halve the onions and cut them into fine pieces
Heat the oil in a frying pan. Fry the onions and courgettes for 3-4 minutes. Add the chopped tomato pulp just before the end of the cooking time. Season with salt, sugar, oregano and pepper. Crumble the feta with your hands. Add the zucchini mixture and feta to the couscous and mix in
Put the tomatoes in an ovenproof casserole dish, season the couscous mixture with salt and pepper again and fill it into the tomatoes. Either put the lid on the tomatoes or simply place them in the casserole dish. Pour on the stock and cook in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 15 minutes