Wash the zucchini, remove the ends at the top and bottom, peel thinly and then cut into slices, about 3 to 4 mm. Peel the onion and chop finely. Core the tomatoes and cut very finely. Finely chop the garlic as well.
Heat the oil in a saucepan and add the zucchini slices. Fry a little while stirring. Then add the garlic, onion and thyme and continue to sweat while stirring. When the onions are translucent, add the tomato paste and finely chopped tomatoes, stir in, pour in the vegetable stock, stir again and simmer for 20 minutes. Stir occasionally.