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 fully combined and sugar is dissolved.
03 - Arrange the sliced onions, carrot pieces, and halved baby potatoes in an even layer at the bottom of a 6-quart or larger slow cooker.
04 - Place the seasoned beef roast directly on top of the vegetable bed. Pour the prepared marinade over the beef, ensuring the meat and vegetables are 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 transfer the cooked beef roast and vegetables to a warm serving platter using tongs or a slotted spoon. 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, skimming any excess fat from the surface if desired.
08 - Whisk together cornstarch and water in a small cup until smooth to create a slurry. Gradually whisk the slurry into the simmering liquid. Continue cooking for 2-3 minutes, stirring constantly, until the gravy thickens to a rich, glossy consistency.
09 - Shred the beef using two forks or meat claws. Arrange the beef and vegetables on plates or a serving platter. Ladle the hot soy garlic gravy generously over everything.
10 - Scatter the sliced scallions and toasted sesame seeds over the top as a final garnish. Serve immediately while hot.