Season the chicken. In a bowl, combine chicken, salt, pepper, ginger, garlic, soy sauce, and rice vinegar. Stir well, then mix in the egg white.
Let it sit for 10–15 minutes while you prep the coating and oil.
Heat the oil. Pour 1.5–2 inches of oil into a heavy pot. Heat to 325°F (165°C). Keep a thermometer clipped to the side for steady temperature.
Coat with starch. Place potato starch in a shallow bowl.
Working in batches, dredge chicken pieces, pressing to coat. Shake off excess. The coating should look thin and powdery, not clumpy.
First fry. Fry chicken in batches at 325°F for 4–5 minutes, until lightly golden and just cooked through.
Don’t overcrowd the pot. Transfer to a rack set over a sheet pan.
Raise the heat. Bring the oil to 375°F (190°C) for the second fry. This step sets the crust.
Second fry. Return chicken to the oil in batches for 1.5–2 minutes, until deep golden and super crisp.
Drain on the rack.
Make the sauce. In a large skillet over low heat, melt butter. Whisk in honey, gochujang, soy sauce, ketchup, brown sugar, rice vinegar, and sesame oil. Simmer 1–2 minutes until glossy and slightly thickened.
Turn off the heat.
Glaze the chicken. Add fried chicken to the skillet and toss until every piece is shiny and coated. If the sauce seems thick, add 1–2 teaspoons of water to loosen.
Finish and serve. Sprinkle with sesame seeds and green onions. Serve immediately with rice, pickled radish, or a crisp salad.
A squeeze of lemon brightens everything.