Make shallow cross-wise scores on both sides of the flank steak about 1-inch apart.

In a large food storage bag, mix together the garlic, sake, and dwaenjang. Place the steak in the bag and seal. Massage the bag so that the steak is fully coated. Refrigerate and let marinate overnight or at least 8-12 hours.

Preheat your grill to high. Carefully place the steak on the grill, cover and let cook for about 4-5 minutes. Note: I used a gas grill.

Flip over, cover the grill, and cook another 4 minutes. Flank steak is best enjoyed when cooked medium-rare. To check for doneness, poke the thickest part of the steak with your finger, if it feels spongy, it's probably rare. If it feels spongy with a little give, it's probably more medium-rare.

Place on a platter and tent with foil for about 10 minutes. Slice thinly crosswise (against the grain) to serve.

Place a couple of slices of steak in a leaf of lettuce, wrap, and eat!