Creating Slow Cooker Korean Beef is simple, and following these steps will ensure a delicious outcome:

1. Prepare the Beef: Cut the beef chuck roast into 1-inch pieces. Trim any excess fat to ensure a leaner dish.
2. Combine Ingredients: In a bowl, mix together soy sauce, brown sugar, rice vinegar, minced garlic, minced ginger, sesame oil, and red pepper flakes if using.
3. Add to Slow Cooker: Place the beef pieces in the slow cooker. Pour the sauce mixture over the beef, ensuring all pieces are well coated.
4. Cook: Cover the slow cooker and cook on low for 6-8 hours or on high for 3-4 hours, until the beef is tender.
5. Thicken the Sauce (optional): If you prefer a thicker sauce, mix cornstarch with a little cold water to create a slurry. Stir this into the slow cooker during the last 30 minutes of cooking.
6. Garnish: Once the beef is done, sprinkle chopped green onions and sesame seeds on top for added flavor and presentation.
7. Serve: Ladle the Slow Cooker Korean Beef over cooked rice or alongside steamed vegetables.

By following these straightforward steps, you’ll have a comforting and flavorful dish ready to enjoy!