Prepare all of the ingredients.
Add pork, garlic, onion, green chilies, salt, pepper and chicken broth to slow cooker. Cover and cook on low for 8-10 hours.
Remove pork from pot and shred. Remove 1½ cup of onion/garlic/green chili mixture (limited amount of broth) to a bowl. Add pork back to pot and toss.
Using an immersion blender (or regular blender), blitz the onion/garlic/green chili mixture. Add jalapeno, tomatillos, and half of cilantro to mixture and blitz until you make a smooth salsa.
Warm tortillas on a griddle, in the microwave (wrapped in a damp paper towel) or in the oven (wrapped in aluminum foil).
To serve, place a portion of pork on the tortilla, top with some of the salsa, a dollop of sour cream,, a sprinkle of cheese and cilantro.