01 - Whisk together soy sauce, brown sugar, sesame oil, rice vinegar, gochujang, garlic, ginger, and black pepper in a large bowl. Add chicken thighs and toss to coat thoroughly. Marinate for at least 15 minutes, or refrigerate overnight for optimal flavor penetration.
02 - Heat vegetable oil in a large grill pan or skillet over medium-high heat. Remove chicken from marinade, allowing excess to drip off. Cook chicken for 4-5 minutes per side until charred edges develop and internal temperature reaches 165°F. Let rest for 5 minutes before slicing into strips.
03 - Divide cooked rice evenly among four serving bowls. Arrange sliced chicken, shredded carrots, cucumber slices, purple cabbage, and green onions on top of the rice. Sprinkle with sesame seeds for garnish.
04 - Top bowls with optional accompaniments such as kimchi, additional gochujang or sriracha for heat, fresh lime wedges, and cilantro. Serve immediately while chicken is still warm.