Preheat broiler.

Place red bell peppers on a small broiling pan.

Broil 5 inches from heat source until peppers turn black and blister, turning as needed to roast evenly.

Place roasted peppers in a sealed plastic bag and let steam for 30 minutes.

Remove peppers from the bag.

Gently peel off the blackened skin.

Cut the roasted peppers into strips.

In a large skillet over medium heat, heat olive oil.

Sauté bell pepper strips, zucchini strips, chopped onions, and minced garlic for 10 minutes, or until onions are softened.

Add tomato sauce, salt, dried red pepper flakes, and optional grilled chicken breast strips to the skillet.

Reduce heat to low, cover, and simmer for 10-15 minutes.

Serve the sauce over cooked fettuccine.