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 evenly. Cover and refrigerate for at least 30 minutes, up to 2 hours for deeper flavor penetration.
03 - While chicken marinates, shred the carrots and cabbage, slice the cucumber and avocado, and thinly slice the green onions. Cook rice if not already prepared.
04 - Combine mayonnaise, gochujang, rice vinegar, and honey in a small bowl. Mix until smooth and creamy. Set aside until 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. Remove from heat and let rest for 5 minutes before slicing against the grain.
06 - Divide cooked rice evenly among four bowls. Arrange sliced BBQ chicken, carrots, cucumber, purple cabbage, and avocado on top of the rice in sections.
07 - Drizzle gochujang mayo generously over each bowl. Sprinkle with sliced green onions and sesame seeds. Serve immediately while chicken is still warm.