In morning or day before, place pork roast in crock pot. Cover with about 1 Cup of the salsa and dry onion soup mix. You can also add a little water but don't add too much as this will make it's own juice. cook on low for 8 hours or until it can easily be pulled aprt by a fork. Let cool, shred pork with two big forks, drain excess liquid. Add the rest of the salsa, the sour cream, half the olives, and the garlic chili sauce and chiles if using.
Take three plates and pour some enchilada sauce on one plate, leave one empty, and put the shredded cheese on the other. Dip your tortilla to cover with sauce on both sides, place on empty plate, fill with some of the meat mixture and top with shredded cheese. Roll up tortilla best you can and place in baking dish. Continue until you run out of mixture or room in pan. Pour remaining enchilada sauce, salsa and shredded cheese on top and bake at 350 for approximately one hour or until browned and bubbly. Garnish with more black olives and green onion (if desired). Serve with more salsa and sour cream.