1. Cut the flank into 3/4 inch wide strips. Place it in a bag and then make the teriyaki sauce.
2. Place the soy sauce, sugar, and ginger root slices and let it come to a boil. Let it simmer for 5 minutes and then remove the ginger.
3. Add the sauce into the bag with the steak and let it marinade. Once marinaded place them on a stick and grill them.