In a mixing bowl, whisk the egg and season with a bit of salt and pepper. In another bowl, combine cornstarch and flour. Dip the chicken pieces into the egg, then dredge in the flour mixture to coat evenly.
Heat oil in a deep skillet over medium-high heat. Fry the chicken in batches until golden brown and cooked through, about 5–6 minutes per batch. Drain on a paper towel-lined plate.
In a small saucepan or clean skillet, combine soy sauce, honey, rice vinegar, ketchup, brown sugar, sesame oil, garlic, and ginger. Bring to a simmer over medium heat.
Stir together 1 tsp cornstarch and 2 tbsp water in a small bowl. Add to the simmering sauce and stir until thickened and glossy, about 1–2 minutes.
Add the crispy chicken to the sauce and toss to coat thoroughly. Sprinkle with sesame seeds and green onions.
Serve hot over white rice, jasmine rice, or noodles.