In a large bowl, whisk together soy sauce, brown sugar, honey, gochujang, rice vinegar, sesame oil, garlic, and fresh ginger until well combined. Add the chicken thighs, ensuring they are coated in the marinade. Let marinate for at least 20 minutes.

Combine shredded green and red cabbage with julienned carrots. In a separate bowl, whisk together mayonnaise, rice vinegar, sugar, salt, and black pepper. Pour the dressing over the cabbage mixture and toss well.

Heat a skillet over medium-high heat and add a splash of cooking oil. Once hot, add the marinated chicken. Cook for about 6-7 minutes on each side until nicely charred and cooked through.

In the same skillet, reduce heat to medium and add butter. Split the buns and place them cut-side down in the skillet. Toast until golden brown.

Assemble your Korean BBQ Chicken Sandwich by placing sliced chicken on the bottom half of the toasted bun. Top with a scoop of cabbage slaw and sprinkle with sesame seeds. Add the top bun and serve.