In a bowl, whisk together soy sauce, brown sugar, honey, gochujang, rice vinegar, sesame oil, minced garlic, and grated ginger until smooth. Coat chicken thighs in the marinade and let marinate for at least 20 minutes.

Combine shredded cabbage and julienned carrot in a bowl. In a separate bowl, mix mayonnaise, a splash of rice vinegar, sugar, salt, and black pepper until creamy. Toss mixture with the cabbage and carrot, then refrigerate.

Heat a skillet over medium-high heat and add the marinated chicken thighs. Cook for 6-7 minutes each side until golden brown and internal temperature is 165°F (75°C). Let rest before slicing.

In the same skillet, melt a pat of butter and toast the cut sides of the buns until golden and crispy, about 2-3 minutes.

Assemble the sandwich with chicken slices, top with slaw, and place the top bun. Serve immediately.