Prep the chicken. Pat chicken dry and cut into 1-inch pieces.
Dry chicken browns better and stays crisp.
Season and coat. In a bowl, whisk eggs with salt and pepper. In another bowl, mix cornstarch and flour. Dip chicken in egg, then toss in the dry mix until evenly coated.
Shake off excess.
Heat the oil. Add 1–1.5 inches of oil to a heavy pot or deep skillet. Heat to about 350°F (175°C). If you don’t have a thermometer, the coating should sizzle briskly when a test piece is added.
Fry in batches. Fry chicken without crowding, 4–5 minutes total, turning as needed.
Remove when golden and cooked through. Drain on a rack or paper towels. Repeat with remaining chicken.
Optional double-fry for extra crunch. Increase oil temp to about 375°F (190°C).
Return fried pieces for 30–60 seconds until extra crispy. Drain again. This step helps the crust resist the sauce.
Make the sauce. In a skillet or wok, combine orange juice, zest, soy sauce, sugar or honey, vinegar, garlic, ginger, and red pepper flakes.
Bring to a simmer over medium heat, stirring to dissolve sugar.
Thicken the sauce. Stir the cornstarch slurry, then add it to the simmering sauce. Cook 30–60 seconds until glossy and slightly thick. If too thick, add a splash of water.
Stir in sesame oil if using.
Coat the chicken. Add crispy chicken to the skillet and toss quickly to coat. Heat just until everything is glazed. Don’t simmer too long, or the crust softens.
Garnish and serve. Sprinkle with sesame seeds and green onions.
Serve over rice with steamed broccoli on the side.
Air fryer option. Toss coated chicken with 1–2 tablespoons oil. Air fry at 390°F (200°C) for 12–15 minutes, shaking halfway, until crisp and cooked through. Toss with sauce as above.