First put the onions, leeks, garlic, peppers, zucchini and mushrooms in a large pot.
Stir, cover and let it come to a boil, then reduce the heat and let the mixture simmer for 20 to 30 min. until the vegetables soften.
Take off the lid from the pot and increase the heat for the final 10 min. of boiling if you want to thicken the sauce.
Sprinkle with olives and spices. Served the dish hot or cold, decorated with spices.