Preheat the oven to 275°F.
Cut pork into large chunks, as needed, to fit into Dutch oven
In a small bowl, mix oil, garlic, chili powder, cumin, oregano, salt and pepper. Rub pork pieces all over with spice mix and place pieces into Dutch oven.
Juice orange and 1/2 of lime and pour the juice over the pork. Cut second half of lime into 4 chunks and place around the pork. Tuck prepared jalapeno and onion around pork pieces.
Cover Dutch oven and cook on center rack of 275°F degree oven for 3 - 5 hours or until internal temperature taken with a digital meat thermometer is at least 150°F degrees. Remove from oven and allow meat to rest for 10 minutes in Dutch oven. Transfer pork to a baking sheet and shred into bite size pieces.
Preheat oven broiler to High. Place shredded pork on baking sheet under the broiler for 4 - 8 minutes until meat edges are browned and crispy.
Serve warm on tortillas with your favorite toppings.