In a 4- or 6-quart pressure cooker place chicken, carrots, mushrooms, sweet pepper, onion, garlic, undrained tomatoes, and chicken broth.
Lock lid in place. Place pressure regulator on vent pipe (if you have a first-generation cooker). Over high heat, bring cooker up to pressure. Reduce heat just enough to maintain pressure and pressure regulator rocks gently; cook for 8 minutes.
Quick-release the pressure. Carefully remove lid.
Add zucchini and couscous to cooker. Cover loosely (do not lock lid) and let stand about 7 minutes or until couscous is tender. Season with salt and black pepper to taste. Sprinkle with parsley. Makes 4 main-dish servings (5-1/2 cups).