Stir the vinegar and salt into the water, add the wings, and soak for 10–15 minutes.
Drain and pat the wings completely dry.
Add the red chili powder, garlic powder, black pepper, salt, lemon juice, and mustard paste; massage well and rest for 10–15 minutes.
Whisk the flour, garlic powder, red chili powder, and salt in a shallow dish.
Heat 2–3 inches of oil to 340–350°F (170–175°C).
Coat a wing in flour, dip it in the ice-cold water, then coat it in flour again, pressing firmly each time.
Fry 5–6 pieces at a time for 4–5 minutes, turning once, until deep golden and 165°F (74°C) inside.
Drain on a wire rack and repeat with the remaining wings.