Peel and quarter onion, slice garlic cloves and layer on bottom of large crock pot.
In a separate bowl, combine remainder of ingredients. Quickly whisk ingredients to make a sauce. The sauce doesn't need to be smooth.
 
Pour about half of the liquid mixture over the onion and garlic.
 
Place 4-5 pounds sirloin pork roast in crock pot. Pour remainder of ingredients over the roast.
 
If you do not have time to make sauce, use two bottles of hickory smoked or honey barbecue sauce.
 
Cover and place on low setting for about 10 hours or high setting for 6 hours. If possible, cook pork for 2 hours on high and then turn setting to low until meat is tender enough to pull apart (about 8 hours total).
 
Use tongs to pull pork into shredded pieces. Place on a bun and serve with pickles. For a full meal, place pulled pork on a platter and serve with side dishes.