01 - Pat the beef chuck roast completely 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 sugar dissolves and mixture is uniform.
03 - Place sliced onions, carrot pieces, and halved baby potatoes in an even layer at the bottom of a 6-quart or larger slow cooker.
04 - Lay the seasoned beef roast directly on top of the vegetable bed. Pour the prepared marinade over the beef, ensuring it coats the meat and drizzles down over the vegetables.
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. 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 on the stovetop.
08 - Whisk together cornstarch and water in a small bowl to create a smooth slurry. Gradually whisk the slurry into the simmering liquid. Continue cooking for 2–3 minutes, stirring constantly, until gravy reaches desired consistency.
09 - Shred the beef using two forks into bite-sized pieces. Arrange meat and vegetables on plates or a serving dish. Ladle hot soy garlic gravy generously over the top.
10 - Scatter sliced scallions and toasted sesame seeds over the plated dish just before serving.