Cut chicken into 1/2-inch pieces. In a large bowl combine half of the green onion, the minced garlic, rice or white wine vinegar, soy sauce, the 1 tablespoon oil, the crushed or ground red pepper, and the black pepper. Add the chicken pieces; stir to coat. Cover and let stand 30 minutes at room temperature or for 1 hour in refrigerator. Drain, reserving marinade.
Heat remaining oil in a large skillet; add chicken pieces. Cook and stir about 3 minutes or until no longer pink. Stir cornstarch into reserved marinade. Add to skillet. Cook and stir until thickened and bubbly. Spoon evenly atop bread shell. Sprinkle with Monterey Jack and mozzarella cheeses. Bake, uncovered, in a 400 degree F. oven for 12 minutes. Top with remaining green onion and nuts. Return to oven for 2 minutes more. Makes 6 main-dish servings.