Pat the pork dry with paper towel.
In a small bowl, combine the oregano, cumin, salt and olive oil to form a paste. Rub it all over the pork.
Place the onion and garlic into the base of the slow cooker, then place the pork on top. If your pork has a fat cap, place it fat-side up. I usually remove the fat cap before serving, but you can leave it on if you prefer.
Pour over the orange juice and lime juice.
Cook on Low for 10 hours or High for 7 hours, until the pork is tender enough to shred easily with two forks.
Transfer the pork to a large chopping board or tray and allow it to cool slightly. Remove and discard the fat cap if desired, then shred the pork using two forks.
Spread the shredded pork into a large oven tray. Spoon over about 1 cup of the cooking liquid, tossing to coat.
Bake at 240°C fan-forced for 10 - 15 minutes. Toss the pork, adding a little more cooking liquid if it looks dry, then return to the oven for another 5 - 10 minutes, or until the edges are crispy and caramelised.
