Add the steaks to the slow cooker. Add the brown sugar, soy sauce, sesame oil, garlic, ginger, and red pepper flakes.
In a small bowl, whisk together the water and corn starch. Pour over everything in the slow cooker.
Mix everything together, I do this by flipping over the steaks into the sauce.
Place the lid on the slow cooker and cook on LOW for 5 hours.
Serve with your desired sides, topped with green onion and toasted sesame seeds.
