In a mixing bowl, whisk together soy sauce, brown sugar, honey, gochujang, rice vinegar, sesame oil, minced garlic, and grated ginger until smooth. Add boneless, skinless chicken thighs to the marinade, ensuring they are fully coated. Let the chicken marinate for at least 20 minutes at room temperature or refrigerate for up to 2 hours for enhanced flavor.

In a large bowl, combine shredded green and red cabbage with the julienned carrot, mixing well for even distribution. In a separate bowl, whisk together mayonnaise, rice vinegar, sugar, salt, and pepper to create a dressing. Pour the dressing over the cabbage mixture, tossing to combine, and refrigerate for at least 15 minutes.

Heat a skillet or grill pan over medium-high heat until hot. Remove the marinated chicken from the marinade, allowing any excess to drip off, then place it in the pan. Cook for 6-7 minutes on each side until cooked through. Transfer the chicken to a plate and let it rest before slicing.

While the chicken rests, take brioche or potato sandwich buns and spread a small amount of butter on the insides. Place buns, buttered side down, onto the skillet or a separate pan over medium heat. Toast for about 2-3 minutes, until golden brown and crispy.

Start by placing a sliced chicken thigh on the bottom half of a toasted bun, drizzling with a bit of the reserved marinade for extra flavor. Top with the chilled cabbage slaw, adding a delightful crunch. Complete your Korean BBQ Chicken Sandwich with the top half of the bun.