Pound chicken breasts to an even 1/2-inch thickness. In a shallow dish, whisk together flour, cornstarch, salt, and pepper. Coat each chicken breast in the flour mixture.

In a small bowl, whisk together 1/4 cup gochujang, soy sauce, 1 tbsp rice vinegar, sesame oil, garlic, and ginger to create the BBQ sauce. In another small bowl, stir together mayonnaise, 1 tsp gochujang, and lime juice for the mayo.

In a medium bowl, combine the shredded cabbage, carrots, 2 tbsp rice vinegar, and sugar. Toss to combine and set aside.

Heat neutral oil in a large skillet over medium-high heat. Cook the dredged chicken for 4-6 minutes per side, until golden brown and cooked through. Remove from skillet.

Pour the BBQ sauce into the skillet and simmer for 1-2 minutes until slightly thickened. Return the chicken to the pan and toss to coat. Serve the sauced chicken on toasted brioche buns with gochujang mayo and the quick slaw. Garnish with sesame seeds and green onions.