Wash the peppers and zucchini and cut into small strips. Peel the onion and dice it a little coarser.
Heat a pan. Fry the onions in a little olive oil until they turn brown. Fry the pepper strips. After about 5 minutes add the zucchini and fry for 5 minutes. Deglaze with about 2 cups of hot water. Add tomato paste and broth. Let simmer until the vegetables reach the desired consistency. Season to taste and serve.