In a large skillet, heat the oil over high heat
When the skillet is hot, add in the pork and sear the pieces for about 2-3 minutes per side.
Put the pork back in the 6 Quart Crock Pot
Add in the onion, soda, chipotle, garlic and seasonings
Cover and cook on low for 8 hours
After 8 hours check to make sure the pork shreds easily (that's when it's done slow cooking)
Line two large baking sheets with foil
Using a slotted spoon, take pork from the slow cooker and place it in an even layer on the lined baking sheets
Place each sheet of pork under the broiler in periods of five minutes, ladling more sauce from the Crock Pot and stirring the pork carefully between five minute sessions.