Soak the chickpeas overnight. Drain the chickpeas, then cook in water for about 30-60 minutes. You have to be done.
Peel and chop the potatoes and garlic. Clean and chop the vegetables.
Heat the oil in a large saucepan. Sauté the potatoes, garlic and onions in it. Add 1 tablespoon harissa and a pinch of each of the spices. Steam everything for 2 minutes while turning. Add the stock, carrots, peppers and tomatoes. Let everything simmer over a low heat for 20 minutes.
Drain the chickpeas. Add to the tagine with zucchini. Let everything simmer over low heat for about 10 minutes. Finally, season with salt and pepper.