Spray your slow cooker with non-stick cooking spray, or place a slow cooker liner in the crockpot.
Place all the ingredients except the sesame seeds and green onions into the slow cooker.
3 pound stir fry sliced beef, ½ onion, ½ cup brown sugar, ¼ cup soy sauce, 6 cloves garlic, 1 teaspoon minced ginger, 1 tablespoon rice wine vinegar, 1 tablespoon sesame oil, Salt and black pepper, 1 tablespoon cornstarch
Toss well to separate the beef.
Cover and cook on high for 2-3 hours or on low for 4-6 hours
Toss the beef and pull apart any strips of meat that are stuck together.
Remove ¼ cup of the drippings from your slow cooker and put it in a small bowl.
To the bowl, add the cornstarch slurry and stir to combine.
Add the mixture back to the slow cooker and continue cooking for 30 minutes to thicken your sauce.
Garnish with sesame seeds and green onion slices if desired.
Sliced green onions, Sesame seeds