Meanwhile, heat a Dutch oven or large wide saucepan over medium-high heat. Add oil; cook eggplants and onion, stirring often, until softened, about 5 minutes. Stir in zucchini, yellow pepper and garlic; cook, stirring occasionally, until softened, about 5 minutes. Stir in tomatoes, chickpeas, hot pepper flakes and remaining salt and pepper; bring to a boil. Reduce heat to medium-low, cover and cook, stirring occasionally, for 20 minutes. Uncover and continue cooking, stirring occasionally, until vegetables are softened and tomatoes form a thickened sauce, about 20 minutes.