Cut the onion in half and thinly slice. Slice the limes into wedges. Set lime wedges aside.
Pat the pork loin dry with a paper towel and cut into ½ inch strips. Season pork with spice mixture of cumin, chili powder, and smoked paprika. (Regular paprika will also work, but smoked paprika adds a nice dimension to the flavor). Massage spice into pork strips.
Heat 1 tablespoon of oil in a skillet over medium-high heat. Add onions and cook until they soften (about 2-3 minutes).
Add the pork strips and allow to cook for three minutes without stirring to allow time for them to sear. Stir and continue to cook pork until it is cooked through and onions begin to brown and caramelize (about 3-4 more minutes). Season with a pinch of salt and pepper.
While the pork is cooking, wrap the tortillas in a damp paper towel, place on a plate, and microwave for 30 seconds. Keep them warm by wraping tortillas in a kitchen towel or foil until ready to serve.
Serve pork tacos with lime slices, warmed tortillas, and fresh orange salsa.
