Prep the chicken: Pat wings dry. Season with salt and pepper.
Make the batter: In a bowl, whisk together flour, cornstarch, and baking powder. Add the egg and cold water to create a thick batter.
Heat the oil: Fill a heavy-bottomed pot with oil (about 2 inches deep). Heat to 330°F (165°C).
First fry: Dip chicken in the batter and fry in batches for 7–8 minutes until pale and cooked through. Remove and drain.
Increase heat: Raise oil temp to 375°F (190°C). Re-fry the chicken for 2–3 minutes until golden and extra crispy. Drain on a rack.
Make the sauce: In a saucepan, combine gochujang, soy sauce, honey, vinegar, sesame oil, garlic, and ginger. Simmer for 2–3 minutes until slightly thickened.
Coat the chicken: Toss hot fried chicken in the warm sauce until evenly coated.
Garnish and serve: Sprinkle with sesame seeds and green onions. Serve immediately!