1Slice onion fairly thick and lay at the bottom of a crock pot. Add the water, then the pork shoulder. Crush/slice the garlic onto of the pork, then add the can of chili. Set on low and let it go for overnight (I let mine go for about 16 hours. Needless to say, it didn't need that long, but it certainly doesn't hurt it!)
2In a large pot, add oil then flour when combined, slowly add the reserved pork stock and water, stirring avoid lumps. Add canned tomatoes and seasonings.
3If you can, blend half the roasted green chilies till smooth and chop the rest. If that's too much of a pain, you can skip that and just chop the whole lot and add them to the sauce.
4Next shred your pork and add that to the sauce.
Cook on low heat for an hour to blend. Stir when needed.
5Pre-heat oven to 350. In a 9 x 13 pan place a triple layer of corn tortillas. Then add a layer of the chili on top of that add a layer of the cheese. Then add another layer of tortillas then meat.
Bake in the oven for 30 minutes uncovered, then add a final layer of cheese. Bake another 10-15 minutes till the cheese is melted.
(You could easily use a smaller baking dish and freeze the rest of the chili)
Serve with sour cream/lettuce/salsa/green onions and whatever other toppings you enjoy.
6Note: You'll want to serve this in bowls as it's a loose dish.
Also, don't be afraid to play around with the ingredients. If you want more heat you can saute (or roast!) some jalapeno and add them to the sauce.