Preheat oven to 425 degrees F. Cut sweet peppers and Anaheim pepper in half lengthwise. Remove seeds and membranes. Place pepper halves, cut side down, on a lightly-oiled-foil-lined baking sheet. Roast for 20 minutes or until skins are blistered. Wrap pepper halves in the foil; let stand for 10 minutes to steam. Peel and discard pepper skins. Coarsely chop peppers.
In a blender container or food processor bowl, combine peppers, garlic, oil, salt, and cumin seed. Cover and blend or process until smooth. (Sauce may be stored in covered container in refrigerator up to 10 days before using.)
Place bread shell on a preheated baking stone or 12-inch pizza pan. Spread with the red pepper sauce. Bake in the 425 degree oven for 5 minutes. Top with chicken, green onion, and cheese. Bake 5 minutes more. Top with sour cream, cilantro and, if desired, avocado and sliced peppers. Makes 6 main-dish servings.