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

Place the chicken thighs in a resealable bag and pour the marinade over them. Seal and refrigerate for 1 hour or overnight.

In a large bowl, toss together the shredded cabbage and carrots until well mixed.

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

Preheat a grill pan over medium-high heat. Grill marinated chicken for 6-7 minutes per side until thoroughly cooked.

Remove chicken from heat and let rest for 5 minutes. Slice into strips.

Lightly toast brioche buns until golden brown.

Assemble the sandwich with sliced chicken on the bottom bun, topped with crispy slaw, and garnish with cilantro and sesame seeds.