Healthy Vegetable and Couscous Stuffed Peppers

Name: Healthy Vegetable and Couscous Stuffed Peppers
Ingredients: 6 large red, yellow or orange bell peppers (or a combination), stable-bottomed enough to stand upright; Two 28-ounce cans fire-roasted tomatoes; 1 cup Israeli couscous; 1 tablespoon chopped fresh oregano (about 3 sprigs) or 2 teaspoons dried; Kosher salt and freshly ground black pepper; 3 tablespoons extra-virgin olive oil; 1 medium onion, chopped; 1 medium zucchini, finely chopped; 6 cloves garlic, minced; 3 cups loosely packed baby spinach; 1/4 teaspoon red chile flakes, optional; One 7-ounce block feta cheese, drained and crumbled; 1/2 cup chopped fresh basil (about 12 large leaves)