01 - Pat the beef chuck roast completely dry with paper towels and season generously with salt and freshly ground black pepper on all sides.
02 - Whisk together soy sauce, beef broth, brown sugar, sesame oil, minced garlic, grated ginger, rice vinegar, and gochujang in a mixing bowl until the sugar dissolves completely.
03 - Arrange the sliced onions, carrot pieces, and halved baby potatoes evenly across the bottom of a 6-quart or larger slow cooker.
04 - Place the seasoned beef roast directly on top of the vegetable layer and pour the marinade mixture over everything, ensuring the beef and vegetables are thoroughly coated.
05 - Cover and cook on LOW setting for 8 hours until the beef becomes fork-tender and easily shreds apart.
06 - Carefully remove the beef roast and vegetables from the slow cooker and transfer them to a warm serving platter, covering loosely with foil to maintain temperature.
07 - Pour the cooking liquid from the slow cooker into a medium saucepan and bring to a gentle simmer over medium heat.
08 - Whisk together cornstarch and water in a small cup until smooth, then gradually whisk this slurry into the simmering liquid. Continue cooking for 2-3 minutes while stirring constantly until the gravy reaches your desired thickness.
09 - Shred the beef using two forks or meat claws, then arrange alongside the vegetables. Drizzle generously with the soy garlic gravy and garnish with thinly sliced scallions and toasted sesame seeds.