In a large bowl, whisk together soy sauce, brown sugar, honey, gochujang, rice vinegar, sesame oil, minced garlic, and grated ginger until smooth. Add chicken thighs, ensuring they are well coated. Cover and marinate for at least 20 minutes or up to 2 hours.

In another bowl, combine shredded cabbage and julienned carrots. In a separate small bowl, whisk mayonnaise and sugar, then drizzle over the cabbage mixture. Toss gently, cover, and chill for about 15 minutes.

Heat a skillet over medium-high heat. Add oil and marinated chicken thighs, cooking for about 6-7 minutes on each side until caramelized and cooked through. Remove from heat and let rest before slicing.

In the same skillet, melt butter over medium heat. Cut buns in half and place them cut side down in the skillet. Toast for 2-3 minutes until golden.

Layer sliced chicken on the bottom half of the toasted bun. Drizzle with extra marinade if desired, then top with cabbage slaw. Place the top bun and enjoy your sandwich!