Place the eggplant cubes in a colander, and sprinkle with approximately 1 tablespoon of salt and toss to coat. Place in the sink and let it drain for approximately 30 minutes. Pat the eggplant dry with paper towels. (Do not rinse.)
Heat 2 tablespoons olive oil over medium-high heat in a large heavy skillet or sauté pan. Add the eggplant, reduce the heat to medium, and cook for 3-4 minutes, stirring often, or until lightly browned and tender. Transfer to a bowl.
Add 1 tablespoon olive oil to the hot skillet. Add the zucchini and cook for 2-3 minutes, stirring often, or until lightly browned. Transfer to the bowl with the eggplant.
Add the remaining 1 tablespoon of olive oil to the hot skillet. Add the onion and cook for 3-4 minutes, stirring often, or until softened.
Add the yellow bell pepper and cook for 1-2 minutes or until lightly browned.
Add the garlic, coriander, cumin, paprika, and turmeric. Stir briefly, 10-15 seconds or until the garlic is fragrant.
Add the vegetable broth and bring to a boil, scraping up the browned bits.
Add the diced tomatoes with their juices, the tomato sauce, and chickpeas. Reduce the heat to medium-low and simmer for 8-10 minutes or until thickened.
Add the eggplant, zucchini, and harissa paste and heat through for 1-2 minutes.
Season to taste with additional salt (if needed) and freshly ground black pepper. Stir in the cilantro.
Serve with hot cooked couscous, rice or quinoa.