Step 1: Sear the Beef

1. Season the chuck roast generously with salt and pepper on all sides.
2. Heat sesame oil in a large skillet or Dutch oven over medium-high heat. Sear the roast on all sides until browned, about 2-3 minutes per side. This step locks in the juices and creates a flavorful crust.

Step 2: Prepare the Vegetables

1. Place the sliced onion, minced garlic, and grated ginger at the bottom of a slow cooker or roasting pan.
2. Layer the carrots and potatoes over the aromatics to create a flavorful base for the beef.

Step 3: Make the Sauce

1. In a small bowl, whisk together the soy sauce, gochujang, brown sugar, rice vinegar, sesame oil, and beef broth. Adjust the amount of gochujang based on your preferred spice level.

Step 4: Assemble and Cook

1. Place the seared beef on top of the vegetables. Pour the sauce evenly over the roast, ensuring it covers the meat and vegetables.
2. Slow Cooker Method: Cook on low for 6-8 hours or on high for 3-4 hours, until the beef is fork-tender.
3. Oven Method: Cover the roasting pan tightly with aluminum foil or a lid and cook in a preheated oven at 325°F (165°C) for 3-4 hours.

Step 5: Serve and Garnish

1. Once the roast is cooked, remove it from the pot and shred or slice it as desired.
2. Arrange the beef and vegetables on a serving platter. Drizzle with the sauce and garnish with toasted sesame seeds and sliced green onions.