In a small bowl, whisk together soy sauce, honey, garlic, ginger and pepper flakes. Place chicken in a large shallow dish. Pour soy sauce mixture over chicken, tossing gently. Cover and refrigerate for at least 30 minutes or up to 8 hours.
Heat a large nonstick skillet over medium-high heat. Add chicken and marinade and sauté for 5 minutes or until chicken is cooked through. Add bell peppers and onion and cook for 5 minutes or until vegetables are slightly tender. Add pineapple and cook for 2 more minutes. Sprinkle with cilantro and serve immediately over rice for a complete meal, if desired.
