Sprinkle chicken with salt and black pepper. In a 12-inch skillet cook chicken in hot oil over medium heat for 12 to 15 minutes or until internal temperature of chicken registers 170F on an instant-read thermometer, turning once. Remove chicken from skillet; keep warm.
Add zucchini, sweet pepper, onion, garlic, and the 1/8 teaspoon black pepper to skillet. Add the water; reduce heat. Cover and cook for 5 minutes, stirring once or twice. Stir in tomato sauce and paste. Bring to boiling; reduce heat. Cover and simmer for 5 minutes more, stirring once.
To serve, divide couscous among dinner plates. Place chicken on couscous. Spoon vegetable mixture over chicken and couscous. Sprinkle with feta cheese and serve with lemon wedges. Makes 4 servings.
*Note: For 2 1/2 cups cooked couscous, in a 1-quart saucepan bring 1 1/4 cup water and a dash of salt to boiling. Stir in 1 cup quick-cooking couscous. Remove from heat. Cover and let stand for 5 minutes. Fluff with a fork before serving.