1. Remove husks from tomatillos and rinse them. Place them whole on your oven's broiler rack. Broil and turn them until they're browned on all sides.
  2. Boil the water. Drop in the dried chiles and bring the water down to a simmer. Keep them in until they are soft.
  3. Slice the shiitakes and cook them in a pan with the olive oil until they're tender.
  4. Take the chiles and tomatillos (once they're cooled off) and blend them in a food processor until they make a nice puree.
  5. Put the blended tomatillo-chile mixture in a saucepan and bring it to a boil. Add the cooked mushrooms and bring it back to a boil. Then bring the heat down until the mixture is simmering. Cook for about 10 minutes. Add salt to taste.

A friend gave me this recipe a while back, but I can't remember who it was. Sorry, friend.