Place freezer zip lock baggy inside a container so you can add all the contents of the marinade in it. Add soy sauce, minced onion, brown sugar, sesame oil, sesame seeds, ginger, garlic, and red pepper. Seal the bag and knead all the ingredients together.

Carefully open the bag and place the steak inside. Make sure their is no excess air in the bag then seal. (You can make multiple packages of meat and freeze them at this point) or you can let it marinade for a minimum of one hour prior to cooking. *If cooking a previously frozen steak make sure your steak is completely thawed out--I suggest pulling it out the night before you want to eat it and placing it in the refrigerator.

Pre-heat grill to a medium-high heat and clean.

Remove steak from bag, and reserve marinade. Grill for 10-16 minutes so that the steak is medium-rare to medium (depending on how you like your meat). You never want to london broil to be well done... it will be very chewy and not very enjoyable!

In a sauce pot, place remaining marinade in the pot and cook on medium until the marinade has reduced to half.

Let the steak sit for at least 5 minutes. When you cut the steak, make sure you slice it against the grain into very thin slices. After the steak is cut drizzle the reduced marinade on top.