In a medium mixing bowl, whisk together the mayonnaise and rice vinegar until smooth. Add the shredded cabbage, carrots, and chopped fresh cilantro. Toss vigorously until coated, then refrigerate.

In a small bowl, combine the gochujang, low-sodium soy sauce, brown sugar, sesame oil, minced garlic, and grated ginger. Whisk until the brown sugar dissolves.

Heat vegetable oil in a skillet over medium-high heat. Sear chicken undisturbed for 5-6 minutes until a golden-brown crust forms. Flip and cook for another 4-5 minutes until cooked through.

Reduce heat to medium-low. Pour the gochujang mixture over the chicken and toss continuously until the sauce bubbles and reduces into a thick, glistening glaze.

Melt butter in a separate clean skillet over medium heat. Toast the sesame seed brioche buns cut-side down until the edges are beautifully crisp and lightly browned.

Place the bottom toasted bun on a board. Layer the saucy chicken thighs, spoon over extra glaze, and pile high with the crisp coleslaw. Crown with the top bun and serve immediately.