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 a hot sometimes doubled soft corn tortilla,,,,sorry I never answered your question but I wanted to address authentic first !!!
the best food comes from somewhere deep within a latin neighborhood,,a little corner tienda ,, I have had as many as 250 spanish employees at a time,,,,and they have changed the way i enjoy mexican food !!!