Preheat oven to 350 degrees.
Heat two tablespoons canola oil in a large skillet, or better yet, if you have a removable slow cooker insert. Once the oil is hot, add the pork roast, brown on both sides that have been seasoned with salt.
While the pork is browning, mix together the Mexican oregano, chile powder, chili seasoning and smoked paprika. Place browned pork roast in a slow cooker and sprinkle the top with the spice mix, gently rubbing some of into the meat.
Toss in the garlic and top with the onion rings. Pour in the beer and 1 cup of the green enchilada sauce.
Cook pork on low for about 8 hours. Or until meat is fall off the bone shreddable tender.
Let the pork cool and and place meat onto a large surface that you can fine shred the meat with two forks. I like to use a disposable foil roasting pan. Use a slotted spoon to fish out the onions and add 1 cup of the liquid from the slow cooker to the pork. Shred the pork removing and discarding any large chunks of fat. At this point I like to sprinkle on more red chile powder to add more heat.
Warm the Corn Tortillas: To build the enchiladas, working in two batches, wrap half of the corn tortillas in a clean dish cloth that's been slightly dampened with water under the faucet. Place wrapped tortillas in a gallon zip lock bag, but don't close the bag. Place in microwave and cook for 4 minutes on 50% power.
Build the Enchiladas: I like to use my two 10 x 6.5" Le Creuset baking dishes to make enchiladas two pans of enchiladas. But you can also coat a 9 x 13 casserole dish with non-stick spray. Add ¼ cup of the enchilada verde sauce to each casserole dish or ½ cup to a 9 x 11 dish. Swirl it around to coat the bottom.
Remove one tortilla at a time from bag and place about ¼ cup of the shredded pork in a tortilla shell. Top with 2 Tablespoons of shredded cheese and roll. Place the first enchilada into the casserole dish, seam side down, nestled to one edge of the pan. Repeat with the remaining tortillas, pressing them close together as you build and place them in the pan.
Heat the remaining tortillas and repeat the process.
Once all tortillas are filled and in the casserole dish, pour remaining cup of enchilada sauce over the enchiladas and generously sprinkle with more shredded cheese.
Bake 30 minutes covered or until bubbly.
Serve immediately.
*If you can't find Chimayo chile powder, just increase the regular chili powder to two teaspoons