Cut the chicken breasts into bite-sized pieces. Season them with salt and pepper.
In a large bowl, whisk together the sweet chili sauce, soy sauce, rice vinegar, minced garlic, and minced ginger. Set aside.
In a large skillet or frying pan, heat the vegetable oil over medium-high heat.
Add the chicken pieces to the skillet and cook for about 5-7 minutes, or until they are golden on the outside and cooked through, stirring occasionally.
Mix the cornstarch and water together in a small bowl to create a slurry.
Once the chicken is fully cooked, pour the sauce mixture over the chicken in the skillet and bring it to a simmer.
Stir in the cornstarch slurry to thicken the sauce. Cook for an additional 2-3 minutes, stirring frequently until the sauce is glossy and coats the chicken well.
Remove from heat and garnish with sliced green onions and sesame seeds if desired.
Serve the Sweet Chili Chicken over rice or noodles and enjoy!