Prepare the chicken: Cut the chicken thighs into four equal portions. In a shallow dish, mix the flour, cornstarch, salt, pepper, and garlic powder. In a second dish, beat the eggs. Dip each chicken piece first in the egg, then dredge thoroughly in the flour mixture.
Fry the chicken: Heat about 2 inches of vegetable oil in a deep skillet to 350°F (175°C). Carefully place the chicken pieces into the hot oil, ensuring not to overcrowd the pan. Fry for 5 to 7 minutes per side, until golden brown and cooked through (internal temperature reaches 165°F or 74°C). Remove and drain on a wire rack.
Make the slaw: In a small bowl, combine the shredded cabbage, mayonnaise, rice vinegar, and sugar. Mix well and set aside. This slaw cools the heat.
Prepare the Gochujang glaze: In a small saucepan, combine the Gochujang, soy sauce, honey, brown sugar, sesame oil, ginger, and minced garlic. Heat over medium-low heat, stirring constantly, until the mixture simmers and thickens slightly, about 3 minutes. Remove from heat.
Glaze the chicken: Brush the hot Gochujang glaze generously over both sides of the cooked chicken patties.
Assemble the burgers: Lightly toast the brioche buns. Place a glazed chicken patty on the bottom bun. Top with a slice of provolone cheese if using, followed by a generous portion of the prepared slaw. Place the top bun on the burger.
Notes
For extra heat, add 1/2 teaspoon of Gochugaru (Korean chili flakes) to the glaze mixture.
If you prefer grilling, brush the chicken with oil and grill over medium-high heat until cooked through, then brush heavily with the glaze during the last few minutes of cooking.
Use sesame seed buns instead of brioche for a nuttier flavor profile.