Rub salt on the roast and place it in the crockpot to rest for 1/2 to 1 hour (this improves the tenderness of the meat).
In the meantime, chop onions, dice chili's, peel and crush garlic, get your stock ready and pull the spices off the rack.
When the roast has rested, place remaining ingredients in the crockpot and cook on low for 7-8 hours, or until tender.
Remove roast from crock pot and, if desired, make gravy with the ancho chili liquid. Here's how. (Note: I prefer to use arrowroot powder instead of cornstarch)