01 - Whisk together soy sauce, brown sugar, sesame oil, garlic, ginger, gochujang, rice vinegar, sesame seeds, and black pepper in a bowl until well combined.
02 - Add chicken thighs to the marinade, turning to coat thoroughly. Cover and refrigerate for at least 30 minutes, up to 2 hours for deeper flavor penetration.
03 - While chicken marinates, shred carrots, slice cucumber, shred purple cabbage, slice avocado, and chop green onions. Cook rice if not already prepared.
04 - Combine mayonnaise, gochujang, rice vinegar, and honey in a small bowl. Whisk until completely smooth and set aside for serving.
05 - Heat a grill pan or skillet over medium-high heat. Grill marinated chicken thighs for 5-6 minutes per side until cooked through and nicely charred. Rest for 5 minutes before slicing.
06 - Divide cooked rice among four serving bowls. Arrange sliced BBQ chicken, carrots, cucumber, purple cabbage, and avocado on top of the rice.
07 - Drizzle generously with gochujang mayo, sprinkle with chopped green onions and sesame seeds. Serve immediately while chicken is still warm.