Preheat broiler to high and place a rack 4 inches from the heat source.

Place the poblano or Anaheim chiles in a single layer on a baking sheet.

Broil the chiles until the skin is blackened, about 6 to 7 minutes, turning occasionally.

Place the blackened chiles in a large bowl and seal with plastic wrap.

Let the chiles stand until the skin has softened, about 7 minutes.

Peel, seed, and roughly chop the chiles. Use immediately or refrigerate overnight.

Season the pork shoulder with salt and pepper.

Place the seasoned pork shoulder in a slow cooker.

Add the chopped chiles, green enchilada sauce, and quartered tomatillos to the slow cooker.

Turn the pork to coat it with the sauce and vegetables.

Cover the slow cooker and cook on low for 6 to 7 hours, or until the meat is fork-tender.

Remove the pork from the slow cooker to a baking dish.

Shred the pork with two forks.

Tilt the slow cooker and spoon off some of the fat.

Place the shredded pork back in the slow cooker.

Cover and rewarm the pork on high heat.

Season with salt and pepper to taste.

Serve the Slow-Cooker Green Chile Pork with flour or corn tortillas, if desired.