In a medium mixing bowl, combine gochujang, soy sauce, honey, sesame oil, minced garlic, grated ginger, rice vinegar, and black pepper. Whisk until smooth.

Place the chicken thighs in a sealable bag or bowl. Pour the marinade over the chicken, ensuring each piece is well-coated. Refrigerate for at least 1 hour.

In a large bowl, toss together the shredded cabbage and julienned carrots until evenly distributed.

In a small bowl, whisk together mayonnaise, lime juice, and sriracha until smooth. Pour over cabbage and carrots, and mix until coated.

Heat a grill pan over medium-high heat, lightly oil it. Grill the marinated chicken for about 6–7 minutes on each side until cooked through.

Once done, transfer chicken to a cutting board and rest for about 5 minutes before slicing.

Toast the brioche buns in a skillet or toaster until golden brown.

To assemble, place sliced chicken on the bottom half of each bun, top with slaw, garnish with cilantro and sesame seeds, and cap with the top half of the bun.