Start by wiping off the dried chilis with a damp towel. De-stem and de-seed the chilis, but don't worry about getting rid of every last seed.
Roast the chilis for 1-2 minutes in a 450F oven, or you can flash them on a hot skillet for 30-60 seconds.
Place the chilis in a bowl and cover with hot tap water. Let the chilis reconstitute for 20-30 minutes. You can use a small bowl or plate to keep them submerged.
Drain the chilis and discard the soaking liquid. Add the chilis to a blender along with 1/2 onion, 3 cloves of garlic, 1 teaspoon Mexican oregano, 1/2 teaspoon cumin, 1 tablespoon salt, some freshly cracked pepper, 1/4 cup apple cider vinegar, and a splash of water. Blend until you have a thick paste.
Add blender mixture to 2 lbs. of uncooked ground pork and combine well using a spoon or your hands.
I store these in 1/2 lb. chunks using Ziplocs. I keep one in the fridge where it will keep for a few days and store the others in the freezer.