Heat olive oil in Dutch oven (or heavy bottom pan) then add onion.
While onion softens, toss pork with flour to coat. Season with salt & pepper.
Add pork to pan and cook on low heat until browned on all sides.
While pork browns, add garlic and cumin.
Pour in salsa and scrape any browned bits from the bottom of the pot.
Add canned green chilis.
(At this point the mixture can be transferred to a crock pot and cooked on high for 3-4 hours, or low for 8 hours.)
Cook over very low heat for 3-4 hours, stirring regularly, until pork shreds easily.
