Step 1: Prepare the chicken. Pat chicken pieces dry with paper towels. In a medium bowl, toss the chicken with 1 tablespoon of cornstarch until lightly coated. This will help create a slight crispness and thicken the sauce.
Step 2: Make the sweet chili sauce. In a small bowl, whisk together the sweet chili sauce, soy sauce, rice vinegar, sesame oil, remaining 1 tablespoon cornstarch, and 2 tablespoons of water until smooth. Set aside.
Step 3: Cook the chicken. Heat 1 tablespoon of vegetable oil in a large skillet or wok over medium-high heat. Add the chicken in a single layer and cook for 3-4 minutes per side, or until golden brown and cooked through. Remove chicken from the skillet and set aside.
Step 4: Sauté aromatics and vegetables. Add the remaining 1 tablespoon of vegetable oil to the skillet. Add the sliced red bell pepper and broccoli florets, and stir-fry for 3-5 minutes until tender-crisp. Add the minced garlic and grated ginger, and cook for another minute until fragrant.
Step 5: Combine and simmer. Return the cooked chicken to the skillet with the vegetables. Give the prepared sweet chili sauce mixture another quick whisk and pour it over the chicken and vegetables. Stir gently to coat everything evenly.
Step 6: Thicken the sauce. Bring the sauce to a gentle simmer, stirring constantly, until it thickens and becomes glossy, about 1-2 minutes. The cornstarch will work its magic quickly.
Step 7: Serve. Remove from heat immediately. Garnish generously with sliced green onions and sesame seeds. Serve hot over steamed rice, brown rice, quinoa, or noodles. Enjoy your homemade sweet chili chicken recipe!