Julia's Korean-Fried Chicken

Preheat the oven to 200 degrees F (95 degrees C). Set a rack on a foil-lined baking sheet.

Pour oil into a 10-inch cast iron skillet. Clip a candy thermometer to the side of the skillet. Heat over medium-high heat until oil reaches 375 degrees F (190 degrees C), about 10 minutes.

Meanwhile, toss chicken, ginger, and salt together in a large bowl until evenly coated. Spread 1/2 cup potato starch in a shallow dish; dredge chicken to coat completely and evenly. Add remaining 1/2 cup potato starch as needed. Shake off excess and transfer to a plate.

Add chicken to the skillet carefully, working in batches; fry until lightly golden, 2 to 3 minutes. Turn chicken over and fry until an instant-read thermometer inserted into the thickest part registers 175 degrees F (80 degrees C), 2 to 3 minutes more. Transfer to the rack on the prepared baking sheet. Reheat oil between batches to 375 degrees F (190 degrees C).

Return chicken to the skillet in batches and fry again, about 2 minutes per side.

Stir gochujang, oyster sauce, mirin, ketchup, fish sauce, and garlic together in a large bowl. Add cooked chicken and toss to coat. Sprinkle with white and black sesame seeds.