(adapted from The Japanese Grill by Tadashi Ono and Harris Salat. I changed some of the ingredients. I recommend you buy this book)
5 cloves of garlic, finely grated (I used 10 cloves and used a garlic press)
6 TBSP Red Miso (I increased it)
2 TBSP Mirin (I increased this)
2 TBSP Sake
1 TBSP Tobanjan (can use other chili sauce)
2 TBSP sugar
2 pounds skirt steak, cut into 4 pieces, most fat removed
Mix everything together. I used a whisk to make sure it mixed well. Take meat and lay on marinade, turning a few times. I let the meat marinade for two full days. Miso tenderizes the meat. If you are going to cook right away, make sure you marinade it at least for an hour.
Grill about 3 minutes on each side. Do not over cook.