Rub with salt/pepper, oregano, cumin and olive oil.
Spray the bottom of slow cooker with oil spray, add onion, garlic and jalapeño. Place the pork shoulder on top and cook for 8-10 hours in low heat or high for about 4- 5 hours
Remove the pork from slow cooker, cool it down then pull apart with a fork
Heat the vegetable oil in a large sauté pan then fry the pork carnitas until crusty on one side