Preheat oven to 375 degrees. Put some aluminum foil down on a lined baking sheet, then spray it with nonstick spray.
Combine all rub ingredients in a small dish (brown sugar through the dry onion flakes.) Pat your pork with a paper towel if it is wet. Rub the spices generously all over the pork tenderloin and let sit for about 10 minutes.
Cook for 30-35 minutes or until an instant read thermometer reads 145 degrees. Cover with foil and let rest for 10 minutes before slicing very thinly on a diagonal. You could grill the pork tenderloin too if you wanted.
Take a warm tortilla and fill it with meat and whatever fixings you want. Just don't forget the barbeque sauce and ranch! It totally makes it!