Begin by soaking the halved chicken breasts in buttermilk for at least 30 minutes.

In a medium bowl, whisk together 1/2 cup all-purpose flour and 1/2 cup cornstarch to create the coating mixture.

Heat oil in a Dutch oven to 350°F (175°C) and fry the coated chicken for 5–7 minutes until golden brown.

In a saucepan, combine 1/4 cup Gochujang, 2 tablespoons soy sauce, 2 tablespoons honey, and 1 teaspoon sesame oil, whisking over low heat until thickened.

Toast the brioche buns in the oven at 350°F (175°C) for 3–5 minutes until golden.

Assemble the sandwich with cabbage slaw, crispy chicken, Gochujang glaze, scallions, and sesame seeds.

Serve immediately while the chicken is warm and crispy.