Place the roast in a crock pot. Sprinkle liberally with cumin.
Pour ½ to 1 full jar of Salsa (depending on the size of your roast) over the top of the roast.
Cook for 6 hours on high or longer on low.
Remove some of the fat.
Shred the meat.
Serve in warmed tortillas topped with onions, cheese, and cilantro with a squeeze of fresh lime.