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

Place chicken thighs in a resealable bag and pour the marinade over. Ensure each piece is coated, then refrigerate for at least 1 hour.

In a large bowl, shred the green cabbage and julienne the carrots. Toss together.

In a small bowl, whisk together mayonnaise, lime juice, and sriracha until smooth. Pour over the slaw and toss.

Preheat a grill pan to medium-high heat. Remove chicken from marinade and discard leftover marinade. Grill chicken for 6-7 minutes each side.

Transfer chicken to a plate and let rest for 5 minutes.

Lightly toast brioche buns on a griddle until golden brown.

Layer grilled chicken onto buns, add slaw, top with cilantro, and sprinkle sesame seeds.