Heat oil in a heavy-based pot and brown the beef on all sides.
Stir in garlic and lemongrass then Add soy sauce, brown sugar, gochujang, rice vinegar, sesame oil stock and water.
Cover and simmer on low for 2½-3 hours, or until the beef is fall-apart tender.
Remove the beef and shred with two forks.
Return the beef to the sauce and simmer uncovered for 10-15 minutes until thick, sticky and glossy.
Serve and enjoy
