Heat oil in a wok or large skillet set over medium-high heat. Add chicken, onions, garlic and red pepper and stir-fry until chicken is cooked through, about 3-4 minutes. Add soy sauce, rice and pineapple and heat through. Add remaining ingredients, reserving a few green onions to sprinkle on top, and cook a few minutes more. Spoon rice on to a platter, sprinkle with reserved green onions, and serve.