Rinse and dry the pork shoulder. Salt and pepper liberally. Mix the oregano and the cumin with olive oil and rub all over pork. Place the pork in a slow cooker and top with the onion, garlic, and jalapeno. Squeeze over the juice of the orange and add the two halves. Cover and cook on low for 8 to 10 hours or on high 4 hours. Reserve liquid.
Once the meat is tender, remove from slow cooker and let cool slightly before pulling apart with a fork. In a large saute pan, heat the olive oil over high heat. Press the carnitas into the oil and fry until crusty on one side. I added about 1 cup of the juice and vegetables from the crock pot to moisten.
Place about 1/2 inch olive oil in a small pan over high heat. Fry tortillas on one side for about 1 minute. Turn and fold in half. Fry on first side of folded tortilla then turn and fry on the other.
Place meat, a bit of the reserved liquid from the crock pot. Serve with your favorite toppings. Lettuce, tomato, cheese, salsa, etc..
Leftover meat can be refrigerated for 3-4 days.Reheat in microwave, until hot.For longer storage, freeze up to 2 months.Thaw in refrigerator. Reheat per above instructions.