In a bowl, toss chicken pieces with cornstarch until coated.
Heat olive oil in a large skillet over medium heat.
Add chicken and cook until golden and cooked through, about 6 to 8 minutes.
In a small bowl, whisk together orange juice, soy sauce, honey, rice vinegar, garlic, ginger, orange zest, and red pepper flakes.
Pour the sauce over the chicken and stir until it thickens slightly, about 2 to 3 minutes.
Remove from heat and garnish with green onions and sesame seeds before serving.