Whenever I buy miso, I wonder if I could do anything with it other than making soup, especially since it often comes in absurdly large packages. Mysteriously, the package of miso I has some tantalizing tips about its use as a marinade, but no recipe. I poked around online, and the recipes range from crazy complex to just lame sounding, so I made my own version. I used it to marinate chicken prior to BBQing, but I think it'd probably be good with pork or even fish if you're into that sort of thing. It was really delicious, and I highly recommend it.
The ingredients are given in approximate proportions, but you should mix it to taste before putting it on the meat. This made about enough to marinate an entire cut chicken.
2 Tbsp miso (the kind you use will change the flavor of course)
1/3 c. warm water (enough to dissolve the miso)
2 Tbsp cider vinegar
1 tsp honey
1 tsp sugar
1 tsp sesame oil
1 tsp sesame seeds
1 tsp light soy sauce
1 tsp dark soy sauce
I didn't add any salt, as the miso was pretty salty as it is.