1Pat the wings very dry with paper towels. Dry skin is what makes crisp chicken, so do not skip this.
2Whisk the potato starch, flour, baking powder, salt, pepper, and garlic powder in a large bowl. Add the wings and toss until every piece is coated, pressing the coating on. Set on a wire rack and let sit 15 minutes so the coating hydrates and clings.
3Pour the vegetable oil into a dutch oven to a depth of about 3 inches and heat to 325°F, checking with a deep-fry thermometer.
4First fry: lower in half the wings, a few at a time so the oil does not crash. Fry 10 to 12 minutes until pale golden and cooked through. Move to a clean wire rack and repeat with the rest. Let rest at least 10 minutes.
5While the wings rest, make the glaze. In a small saucepan combine the gochujang, soy sauce, honey, brown sugar, rice vinegar, garlic, ginger, and gochugaru if using. Simmer over medium-low heat 3 to 4 minutes, stirring, until syrupy and fragrant. Take off the heat and stir in the sesame oil.
6Second fry: bring the oil up to 375°F. Fry the wings in two batches for 3 to 4 minutes until deep golden brown and very crisp. Drain on the rack.
7Toss the hot wings in a large bowl with the warm glaze until evenly coated. Pile onto a platter and finish with sesame seeds and scallions. Serve right away while the crust is still crackly.
8Let the oil cool completely in the pot before you move it, which takes an hour or more. Strain it through a fine sieve into a jar and it is good for two or three more fries; otherwise seal it and discard it. Never pour frying oil down the drain — it hardens in the pipe.