01 - Pat the beef chuck roast thoroughly dry with paper towels. Season all sides generously with salt and freshly ground black pepper.
02 - In a medium mixing bowl, whisk together soy sauce, beef broth, brown sugar, sesame oil, minced garlic, grated ginger, rice vinegar, and gochujang until the sugar dissolves completely.
03 - Place the sliced yellow onions, carrot pieces, and halved baby potatoes in an even layer at the bottom of a 6-quart slow cooker.
04 - Set the seasoned beef roast on top of the vegetable bed. Pour the prepared marinade evenly over the beef and vegetables, ensuring all components are well coated.
05 - Cover the slow cooker with its lid. Cook on LOW setting for 8 hours, or until the beef shreds easily with a fork.
06 - Carefully remove the beef roast and vegetables from the slow cooker. Transfer them to a large serving platter and cover loosely to keep warm.
07 - Pour the cooking liquid from the slow cooker into a medium saucepan. Bring to a gentle simmer over medium heat.
08 - Stir together the cornstarch and water in a small bowl to create a smooth slurry. Whisk the slurry into the simmering liquid and cook for 2 to 3 minutes, stirring constantly, until the gravy thickens and coats the back of a spoon.
09 - Using two forks, shred the beef into bite-sized pieces. Arrange the shredded beef and vegetables on plates. Drizzle generously with the warm soy garlic gravy and top with sliced scallions and toasted sesame seeds.