Add chunks of pork to the slow cooker

Pour the beer into slow cooker over the pork. Cut the orange and lime in half and juice them directly into the slow cooker.  Place the citrus rinds in the cooker with the pork.

In a separate small bowl add salt, pepper, oregano and cumin. Stir to mix well.

Place the cut onion wedges and garlic in the slow cooker, pushing down between the pork chunks.

Sprinkle spice mixture evenly over the pork and rub it in a little.

Cover the slow cooker and cook on low for 8 hours or until meat pulls apart easily.

Preheat oven to broil.

Remove the pork and onions from the slow cooker and transfer to a heavy duty aluminum baking sheet, let it cool till you can shred it by hand.  Shred pork on baking sheet removing and discarding large chunks of fat.  Spread the pork out into a single layer on the baking sheet.

Put the baking sheet with the pork under the pre-heated broiler for 10 to 15 minutes or until it reaches your desired crispiness level. You will need to pull it out every 3 or 4 minutes and stir up and redistribute the pork for even browning. (Do not leave the pork unattended)

Once it's to your crispiness and brownness liking you're ready to serve it up.