Vegetable Tagine with Dates Lemon

Name: Vegetable Tagine with Dates & Lemon
Ingredients: 2-3 ounces olive oil; 1 onion, large dice; 3-4 tablespoons tagine spice mix; 2 small to medium zucchini, cut into thick, finger-sized pieces; 2 small to medium yellow squash, cut into thick, finger-sized pieces; 2 carrots, peeled and cut into thick, finger-sized pieces; 2 stalks celery, cut into thick, finger-sized pieces; 1 red pepper, seeded and diced large; 1 green pepper, seeded and diced large; 8 wedges of preserved lemon; 12 dates, not pitted; 12-16 green pitted olives; 1 can chickpeas (reserve the liquid in the can); 1 cinnamon stick; 2 bay leaves; Brown rice, spiced quinoa pilaf, or basmati rice for serving (optional)