Prepare the Marinade: In a large bowl, whisk together the gochujang, soy sauce, honey, sesame oil, minced garlic, grated ginger, rice vinegar, and black pepper. Ensure all ingredients are well blended.

Marinate the Chicken: Coat the chicken thighs thoroughly in the marinade. Cover or transfer to a sealable bag and marinate in the refrigerator for at least 1 hour, ideally overnight.

Prepare the Slaw: Mix shredded cabbage and julienned carrots in a bowl, tossing together to combine.

Make the Slaw Dressing: Whisk together the mayonnaise, lime juice, and sriracha until smooth. Mix together with the cabbage and carrots, then refrigerate.

Cook the Chicken: Heat a grill pan over medium-high heat, lightly coat with cooking oil, and grill the marinated chicken for 6-7 minutes per side until cooked through.

Rest and Slice the Chicken: Let the grilled chicken rest for a few minutes, then slice into strips.

Toast the Buns: Toast brioche buns until golden brown on the grille or toaster.

Assemble the Sandwiches: Layer sliced chicken on a toasted bun, top with crispy slaw, fresh cilantro, and sesame seeds. Close the sandwich with the top bun.