Begin by trimming excess fat from your chuck roast. In a mixing bowl, whisk together soy sauce, brown sugar, honey, sesame oil, rice vinegar, grated ginger, minced garlic, and seasonings including red pepper flakes and black pepper. Add thinly sliced onion.

Place the trimmed chuck roast into your slow cooker, ensuring it's submerged in the sauce. Set cooker to low for 8 to 10 hours or high for 4 to 5 hours until tender.

After cooking, remove the roast and shred with two forks. For a thicker sauce, combine cornstarch with cold water and add to the sauce, or simmer some sauce on the stovetop.

Return shredded beef to slow cooker, stir to coat with sauce, and simmer for an additional 10 to 15 minutes.

Serve by spooning beef over cooked rice and garnish with green onions and sesame seeds. Offer kimchi on the side.