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 the 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 onions, carrots, and halved baby potatoes in an even layer at the bottom of a 6-quart or larger slow cooker insert.
04 - Lay the seasoned beef roast directly on top of the vegetable bed. Pour the prepared marinade over the meat and vegetables, ensuring everything is evenly coated.
05 - Cover the slow cooker with its lid. Cook on LOW setting for 8 hours until the beef is fork-tender and easily shreds apart.
06 - Carefully remove the cooked beef roast and vegetables from the slow cooker using tongs. Transfer to a large serving platter and cover loosely with foil 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 - Whisk together the cornstarch and water in a small cup to create a smooth slurry. Gradually whisk the slurry into the simmering liquid. Continue cooking for 2–3 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 beef and vegetables on plates. Drizzle generously with the warm soy garlic gravy.
10 - Scatter the sliced scallions and toasted sesame seeds over the top of each serving as a final garnish.