Prep the chicken: Pat the chicken dry and cut into bite-size pieces. Dry chicken means better browning and a crispier coating.
Make the coating: In a bowl, whisk eggs with a pinch of salt.
In a separate bowl, combine cornstarch, flour, baking powder, salt, and pepper.
Coat the chicken: Dip chicken in the egg, letting excess drip off. Toss in the dry mixture until each piece is well coated. Shake off extra flour-starch to avoid clumps.
Heat the oil: Add 1/2 inch of oil to a large skillet or use a deep fryer.
Heat to about 350°F (175°C). If you don’t have a thermometer, a pinch of coating should sizzle right away but not burn.
Fry in batches: Cook chicken for 3–4 minutes per side until golden and cooked through. Don’t overcrowd the pan.
Transfer to a wire rack or paper towel–lined plate. Tip: For ultra-crisp, do a quick second fry for 1–2 minutes.
Make the sauce base: In a medium saucepan, combine orange juice, zest, soy sauce, sugar, rice vinegar, ketchup, sesame oil, garlic, ginger, and red pepper flakes. Stir and bring to a gentle simmer over medium heat.
Thicken the sauce: Stir the cornstarch slurry, then pour it into the simmering sauce while whisking. Cook 1–2 minutes until glossy and thick enough to coat a spoon.
Adjust sweetness or acidity to taste.
Combine: Place the fried chicken in a large skillet or wok. Pour the sauce over and toss quickly over low heat until evenly coated. Don’t simmer too long or you’ll soften the crust.
Garnish and serve: Sprinkle with scallions and sesame seeds.
Serve over steamed rice with a side of broccoli or snap peas.