Mix together the cumin (1 tablespoon), oregano (1 tablespoon), cayenne pepper (1/2 teaspoon), salt, and pepper in a small bowl.
Rub pork with olive oil until coated, then rub the spice mixture all over the pork. Place in slow cooker.
Mix together the onion, jalapeño, minced garlic, and orange zest. Spread on top of the pork.
Squeeze the orange juice on top of the pork and place the orange rinds in the slow cooker.
Cook on low for 8-10 hours or high for 4-5 hours.
When the pork is done cooking, take the meat out (careful- it will be very tender and will tend to fall apart!) and place on a large platter or dish. Pull meat apart with two forks.
Heat the 3 tablespoons olive oil in a large skillet and fry the pork until crispy.
Meanwhile, toast corn tortillas over gas burners, in the oven, or in a skillet. Or, just microwave them for a few seconds to soften.
Add pork to the tortillas and top with fixings.
The provided nutrition information does not include any added sodium from seasoning to taste, any optional ingredients, and it does not take brands into account. Feel free to calculate it yourself using this calculator or by adding the recipe to Yummly.