Trim off all large pieces of fat and cut the pork in 1 inch pieces. Place in a large bowl and set aside.
Take the two chipotle peppers and break the stem off and shake the seeds out. Slightly break up with hands and place in a dry skillet. Toast over medium heat for 3-4 minutes until aromatic.
Add a couple cups of water and simmer for 5-10 minutes, or until the peppers are tender.
Meanwhile, cut and core the pineapple and place half of it in the food processor. Set the other half aside for now.
Cut the onion into large chunks and remove skin and ends. Place in the food processor with the pineapple.
Add the rehydrated peppers (without the water), garlic, chili powder, vinegar, oregano, and salt. Process until mostly smooth. Slightly chunky is fine.
Pour over the pork and let marinade for 30 minutes. DO NOT let it marinade any longer because the pineapple contains an enzyme that breaks the pork down and causes it to become mushy.
While the pork is marinating, make the pineapple salsa. Cut the remaining half pineapple into bite-size pieces. Dice half of an onion and mix it with the pineapple. Add the lime juice and salt and chill until ready to serve.
Cook the pork in batches on a frying pan. No oil is needed because of the sauce. Do not overcrowd the pan- it took me four batches to cook it all.
Serve with salsa over cauliflower rice, on a salad, or out of a bowl.