Heat oven to 325°F. Place pork roast in shallow glass baking dish. Sprinkle with garlic salt, cumin and oregano. Top with green chiles and onion. Add water to baking dish. Cover with foil.
Bake at 325°F. for 2 1/2 hours or until pork is very tender. With slotted spoon, remove pork and onion from baking dish; reserve liquid.
With 2 forks, shred pork by pulling apart along grain; place in medium bowl. Add about 1/4 cup cooking liquid; mix well. Prepare enchiladas immediately, or cover and refrigerate pork mixture until serving time.
Increase oven temperature to 350°F. Spray 13x9-inch (3-quart) glass baking dish with nonstick cooking spray. Add roasted peppers, green onions, sour cream and 1 cup of the cheese to pork in bowl; mix well. Spread about 2 teaspoons enchilada sauce on each tortilla. Top each with about 1/2 cup pork mixture. Roll up tortillas; arrange, seam side down, in sprayed baking dish.
Top with remaining enchilada sauce. Sprinkle with remaining cheese. Spray sheet of foil with cooking spray; cover baking dish with foil, sprayed side down.
Bake at 350°F. for 45 to 60 minutes or until enchiladas are thoroughly heated.