01 - 
                Place the cornstarch-covered flank steak, toasted sesame oil, chopped garlic, and chopped ginger into your slow cooker.
              
              
              
                02 - 
                In a bowl, combine the soy sauce, brown sugar, and water until the mixture is smooth.
              
              
              
                03 - 
                Pour the mixed sauce over the beef in the slow cooker, ensuring the beef is fully coated.
              
              
              
                04 - 
                Cover the slow cooker with its lid and cook on low for 4 to 5 hours or on high for 2 to 3 hours until the beef is tender.
              
              
              
                05 - 
                If using green onions, add them in the last 30 minutes of cooking. Serve the dish over rice or noodles, garnishing with additional green onions if desired.