Preheat your oven to 250 degrees.
Start with a 5lb boneless pork butt.
Remove the excess layer of fat from your pork butt.
Slice your pork butt into large, thick slices and then then cut your slices into large chunks.
Pour 2 tbl canola oil over the meat and using your hands, rub all of the meat together to ensure that all sides of each piece has been coated in the oil.
In a small bowl, combine the salt, oregano, cumin, chili powder, pepper and chipotle powder together.
In batches, pour over your meat chunks and rub together until all of the seasoning has been rubbed over each side of each chunk.
Smash each piece of garlic with the back of your knife to release the garlic from it's paper exterior.
Do not chop up the garlic clove but so make sure it has a nice 'smash' to it.
Mix in the garlic pieces with the meat.
Cut up two oranges into large pieces and place in a casserole cooking container that will be just big enough to hold all of the ingredients.
Pour the meat / garlic over the oranges and arrange everything to fit nicely and then press down gently to compact the meat and oranges together.
Drizzle the remaining 1/4 cup canola oil on top of the meat and then cover your dish tightly with foil.
Cook in your oven at 250 degrees for two hours. After two hours, increase the heat to 275 degrees for the next hour and a half.
Remove your carnitas from the oven and check for doneness.
Remove the meat to a large cutting board. Using two forks, shred the meat and remove any lingering fat pieces from the meat.
Set your oven to broil.
Pour out the oranges and most of the juices left from the cooking process.
Return the meat to the casserole dish and move your oven rack up to just under the broiler. When your broiler is red hot and ready, slide the carnitas under the broiler and babysit the process.
The edges will start to darken and get crispy.
Once a nice char has been achieved, remove the meat, stir the meat and then return it to the broiler one last time. This whole process should only take a couple of minutes.