In a mixing bowl, whisk orange zest, juice, ketchup, rice vinegar, honey, soy sauce, sesame oil, chili sauce, garlic cloves and 2 tsp cornstarch together until smooth and set aside.
Heat a large pan over medium heat and add 1 Tbsp oil. When oil is hot, add broccoli florets and cook for 5-7 minutes stirring occasionally until tender. Transfer to a plate or bowl and set aside.
In a large bowl, mix chicken pieces 2 Tbsp cornstarch until evenly coated.
Heat the remaining 1 Tbsp oil in the same pan over medium heat. When oil is hot add the chicken and cook 6-8 minutes until browned and cooked through, stirring often and breaking up the pieces with a spoon as needed.
When chicken is cooked, pour sauce into the pan and let it reduce and thicken until it coats the chicken. Stir in broccoli and serve.