In a medium bowl, whisk together soy sauce, brown sugar, honey, gochujang, rice vinegar, sesame oil, garlic, and fresh ginger until smooth. Coat the chicken thighs thoroughly in the marinade, allow to marinate for at least 20 minutes or refrigerate for up to 2 hours.

In a large bowl, combine the shredded green and red cabbage and julienned carrot. In a separate bowl, mix together mayonnaise, sugar, salt, and pepper. Pour the dressing over the cabbage and carrot, toss well to coat. Chill for at least 15 minutes.

Preheat a skillet over medium-high heat. Add the marinated chicken thighs, cooking for about 6-7 minutes per side until fully cooked. Let the chicken rest before slicing.

Butter the cut sides of the buns. Toast them in the skillet until golden brown and slightly crispy.

Assemble the sandwich with a slice of chicken on the bun, drizzle with additional sauce if desired, and add the crunchy cabbage slaw. Serve hot.