In a mixing bowl, whisk together soy sauce, brown sugar, honey, gochujang, rice vinegar, sesame oil, minced garlic, grated ginger, and toasted sesame seeds. Add the chicken thighs and coat thoroughly. Let marinate for at least 20 minutes or up to 2 hours.

In a large bowl, combine shredded cabbage and julienned carrot. In a separate bowl, whisk together mayonnaise, rice vinegar, sugar, salt, and pepper. Pour dressing over cabbage mixture and toss. Refrigerate.

Heat a cast-iron skillet over medium-high heat. Cook marinated chicken for 6-7 minutes on each side or until cooked through. Let rest before slicing.

Split the buns and butter the inner sides. Toast in the skillet until golden brown.

Lay slices of chicken on the bottom half of each bun. Drizzle with BBQ sauce if desired and add cabbage slaw. Place the top of the bun over the slaw.