In a glass bowl, whisk orange juice, orange zest, soy sauce, ginger, garlic, 1-tablespoon olive oil, Sriracha sauce, rice vinegar, brown sugar, and black pepper.
Place the chicken in a ziplock bag and pour 1/3 of the mixture in the bag. Seal the bag and place it in the fridge. Let it marinade for an hour.
Heat 1-tablespoon olive oil on a large non-stick skillet over high heat. Remove chicken from the bag and discard the marinade.
Add chicken, in 2 batches, and cook each batch for 6-7 minutes. Place the cooked chicken on a clean plate. Set aside.
Pour the rest of the marinade into the now-empty skillet and cook until boiling over medium high heat.
In the mean time, whisk together the cornstarch and water in a small bowl. It will be like a white paste. Whisk it into the marinade and let it boil for a minute.
Return chicken into the skillet and cook for 5 minutes or until chicken registers 160 F when a thermometer is inserted in some of the pieces of chicken.
Serve it immediately over rice. Sprinkle it with scallions and black sesame seeds.