Combine the chicken with salt, black pepper, ginger, and water (or rice wine). Mix well and refrigerate for 20 minutes while preparing the sauce and coating.

Whisk together the gochujang, ketchup, honey, soy sauce, brown sugar, water, rice vinegar, garlic, and toasted sesame oil in a saucepan. Simmer over low heat for 3–4 minutes, stirring until glossy. Turn off the heat; reserve until serving.

Mix the potato starch, flour, and baking powder in a bowl. Add the beaten eggs to the marinated chicken and stir to coat. Toss the chicken in the dry mixture, pressing to create a craggy coating. Shake off excess flour.

Heat the frying oil in a deep heavy-bottomed pot to 170°C (340°F). Carefully fry the chicken in batches for 5–7 minutes, depending on piece size, until pale golden and the internal temperature reaches at least 74°C (165°F). Do not overcrowd. Drain on a rack for 3–5 minutes.

Raise the oil temperature to 190°C (375°F). Fry the chicken again in batches for 1–2 minutes until deeply golden and crisp. Return to the rack to drain.

Warm the sauce gently if it has cooled. Immediately before serving, toss the fried chicken with the sauce until lightly and evenly coated. Sprinkle with sesame seeds and scallions and serve at once.