Peel and dice the onions, peel and chop the garlic cloves. Clean and wash the vegetables. Finely dice the zucchinis, cut the carrots and peppers into fine strips.
Heat the oil, sauté the onions and garlic lightly, add the tomato paste, prepared vegetables, herbs and spices. Pour vegetable stock on top and let simmer over low heat for about 15 to 20 minutes. If necessary, add more broth. Season to taste with pepper and sugar, remove the bay leaf and serve.