Wash the thyme, shake dry, remove leaves from the stalks except for something to garnish. Wash and clean both courgettes, cut them in half lengthwise and remove the seeds with a spoon. Place the zucchini in an ovenproof dish. Season with salt, pepper and thyme and sprinkle with 2 tablespoons of oil.
For the filling, bring the vegetable stock to the boil, pour over the bulgur, cover and allow to swell for approx. 15 minutes. Mix bulgur and tomato paste, season with salt and pepper. Stuff the zucchini with it. Cut feta into thin slices and spread on the zucchini.
Bake in a preheated oven (electric cooker: 175 °C/ circulating air: 150 °C/ gas: see manufacturer) for approx. 15 minutes until golden brown.
In the meantime, peel and chop the onions. Heat 1 tablespoon of oil in a frying pan and sauté the onions for about 5 minutes. Add tomatoes, bring to the boil and simmer for about 10 minutes. Chop the tomatoes with a spatula. Season the sauce with salt, pepper and sugar, arrange with the zucchini and garnish with thyme.