In a medium bowl, combine the chicken pieces, sweet chili sauce, soy sauce, grated ginger, salt, and pepper. Mix well to coat the chicken evenly. Cover and let marinate in the refrigerator for at least 30 minutes (or up to 2 hours for more flavor).
Heat the olive oil in a large skillet over medium-high heat. Add the sliced red onion and minced garlic; sauté for about 2 minutes until fragrant.
Add the marinated chicken pieces to the skillet, cooking for about 5-7 minutes, or until they are browned and cooked through.
Toss in the sliced bell pepper and pineapple chunks to the skillet. Stir-fry everything together for an additional 3-4 minutes, allowing the pineapple to caramelize slightly and the veggies to soften.
Remove from heat and transfer the Sweet Chili Pineapple Chicken to a serving platter. Garnish with chopped green onions and a sprinkle of sesame seeds.
Notes
Serve over steamed jasmine rice for a complete meal.