Prep the chicken. Pat the chicken dry with paper towels.
This helps the coating stick and ensures good browning.
Season and coat. In a bowl, whisk the egg. In a separate bowl, mix cornstarch, salt, pepper, garlic powder, onion powder, and paprika. Dip chicken in the egg, then toss in the cornstarch mixture until well coated.
Shake off excess.
Toast the sesame seeds. In a dry skillet over medium heat, toast sesame seeds for 2–3 minutes until golden and fragrant. Transfer to a small bowl and set aside.
Cook the chicken in batches. Heat 1.5 tablespoons oil in a large nonstick or cast-iron skillet over medium-high heat. Add half the chicken in a single layer.
Cook 3–4 minutes per side until golden and cooked through. Transfer to a plate. Repeat with remaining oil and chicken.
Make the sauce. In a small bowl, stir soy sauce, honey, rice vinegar, sesame oil, garlic, ginger, and red pepper flakes.
In a separate small cup, mix the cornstarch slurry.
Thicken the sauce. Reduce heat to medium. Pour the sauce into the empty skillet. Stir in the slurry and simmer 1–2 minutes until glossy and thick enough to coat a spoon.
Glaze the chicken. Return the cooked chicken to the skillet.
Toss to coat evenly for 30–60 seconds. Sprinkle in most of the toasted sesame seeds, saving a pinch for garnish.
Finish and serve. Turn off the heat. Top with remaining sesame seeds and green onions.
Serve hot over rice, noodles, or alongside steamed veggies.