I have to say that if you are attempting to eat an authentic taco,,its not made from ground beef,,,,but shredded  beef  carne asada , lengua,carrbaso    pork or  chicken usually shredded or even chorrizo ,,,please excuse my attempted mexican spelling,,  when you go to a ( authentic mexican restaurant  )  and order a taco it quite often comes on a hard shell, ( because they assume thats how a gringo wants it ),,however when you order an authentic mexican taco it comes on...