Cut up about 7 lbs of pork (shoulder or picnic roast) and put it in a large, deep baking dish. Add salt and pepper.
In a blender put 8 cloves of garlic and 3/4 cup of white vinegar and blend. Pour this over the pork and let it sit.
In a medium sauce pan boil about 15 pasilla peppers (these are dried-basically you are boiling them to make them soft again, about 10 minute rolling boil) Remove from heat and let them cool. When cool, open the chiles up and discard seeds and stems.
Put the chile skins in a blender with about 2 cups of water a pinch of oregano and a pinch of cumin (i try to use water from where I boiled the chiles). Blend-don't worry if you don't get all the seeds cause you are gonna strain it thru a strainer anyway. Strain it and pour over the pork.
Add a little more water if it looks too dry.
Cook in oven on 350 for 3-4 hours or till liquid is almost gone. Meat will look blackened when almost done. There is no need to stir. This is super good and not too spicy. I have cooked this in a pressure cooker too but there is an art to not letting it get too dry.This goes really good with the next recipe...