01 - In a medium bowl, whisk together soy sauce, brown sugar, water, rice vinegar, sesame oil, ginger, garlic, gochujang, and toasted sesame seeds until smooth and well combined.
02 - Place beef chunks in the slow cooker. Pour the prepared sauce over the beef, turning pieces to coat evenly with the marinade.
03 - Scatter half of the sliced green onions over the beef and sauce mixture.
04 - Cover and cook on low setting for 7 hours, or until beef is very tender and can be easily shredded with a fork.
05 - Shred the beef directly in the slow cooker using two forks. Stir thoroughly to coat all pieces with the flavorful cooking liquid.
06 - Serve hot over steamed rice, in lettuce wraps, or with steamed vegetables. Garnish with remaining green onions, sesame seeds, and optional sliced red chili.