Instructions:
- Marinate the Chicken: Combine chicken pieces with soy sauce, grated ginger, minced garlic, black pepper, and mirin/sake. Mix well, cover, and refrigerate for at least 1 hour.
- Prepare the Dry Mix: Whisk together potato starch, all-purpose flour, baking powder, and salt in a large bowl.
- Set up the Wet Batter: Add the ice-cold water to the dry mix. Whisk lightly until just combined. Lumps are fine; do not overmix to prevent gluten development.
- Coat the Chicken: Dredge the marinated chicken pieces thoroughly in the wet batter, shaking off any heavy excess to ensure a thin coating.
- First Fry (Cooking Through): Heat oil in a deep fryer or heavy-bottomed pot to 325°F (160°C). Fry the chicken in small batches for 7–8 minutes until pale golden and cooked through. Remove and drain on a wire rack. Let rest for at least 10 minutes.
- Prepare the Glaze: While the chicken rests, combine Gochujang, soy sauce, honey, rice vinegar, brown sugar, minced garlic, and water in a small saucepan. Simmer over medium heat until slightly thickened (about 3 minutes). Remove from heat and stir in the toasted sesame oil.
- Second Fry (Crisping): Increase the oil temperature to 375°F (190°C). Fry the rested chicken pieces again for 2–3 minutes until deep golden brown and aggressively crisp. Drain immediately.
- Toss and Serve: Place the piping hot, double-fried chicken into a large bowl. Pour the warm glaze over the top and toss quickly until evenly coated. Serve immediately.