Prep the chicken: Pat the chicken dry with paper towels.
Season with salt and pepper, then toss with 2 tablespoons of cornstarch until evenly coated. Shake off excess.
Whisk the sauce: In a bowl, combine orange juice, orange zest, soy sauce, honey, rice vinegar, chicken broth, and sesame oil. Taste and adjust sweetness or salt if needed.
In a separate small cup, mix the remaining 1 tablespoon cornstarch with 1 tablespoon water to make a slurry.
Sear the chicken: Heat 1 tablespoon oil in a large nonstick skillet over medium-high. Add half the chicken in a single layer and cook 3–4 minutes per side until lightly golden and cooked through. Transfer to a plate.
Repeat with remaining oil and chicken.
Sauté aromatics: Reduce heat to medium. In the same pan, add garlic, ginger, and red pepper flakes. Cook 30–45 seconds, stirring, until fragrant.
Don’t let the garlic brown.
Build the sauce: Pour in the orange sauce mixture. Bring to a gentle simmer. Stir the cornstarch slurry, then add it to the pan.
Simmer 1–2 minutes, stirring, until the sauce thickens and turns glossy.
Combine: Return the chicken and any juices to the pan. Toss to coat and simmer another minute so the flavors meld. If the sauce gets too thick, add a splash of water.
If it’s too thin, simmer another minute.
Finish and serve: Sprinkle with green onions and sesame seeds. Serve hot with rice and steamed vegetables.