In a bowl, toss the chicken pieces with cornstarch until well coated.
Heat the vegetable oil in a large skillet or wok over medium-high heat. Add the chicken and cook until golden brown and cooked through, about 5-7 minutes. Remove the chicken from the skillet and set aside.
In the same skillet, add the red and green bell peppers, onion, garlic, and ginger. Stir-fry for about 3-4 minutes until the vegetables are tender.
In a small bowl, whisk together the soy sauce, honey, rice vinegar, and sriracha. Pour this sauce over the vegetables in the skillet.
Return the cooked chicken to the skillet and toss everything together until the chicken is well coated with the sauce. Cook for an additional 2-3 minutes to heat through.
Serve hot, garnished with sliced green onions and sesame seeds.