This is the last installment from Puerto Vallarta, in which Diana learns to eat a taco…Can you believe it took me 5 weeks in Mexico to try a taco?  And I love tacos!  The nice crispy shell, cracking into a million pieces when you bite in, scattering bits of lettuce and tomato and cheese and sour cream and salsa across the table…no, wait!  That was all in a dream!  That was my American taco.  It bears no resemblance to a Mexican taco.  The first thing is, you don’t eat Mexican tacos in a restaurant.  That’s for gringos.  If you want a real taco, you buy it from a street vendor.  Just like pulled pork BBQ in the U.S. – would you ever buy it in a restaurant?  Please!  The best place for BBQ is from one of those beat up trailers on the side of the road, belching smoke into the sky, with a line of cars down the street and nary a food inspector in sight.  So, as I was saying, the first lesson is, you buy tacos from a taco stand.  Here, they’ve got one, or two or three, on every corner.  Number two, forget about the hard shell.  That’s for tostadas, and they’re flat.  Tacos come on soft corn tortillas.  Next – forget about that ground beef in soupy sauce that you make with a packet of spice mix.  Picture instead little mini steaks on the grill that get chopped into pieces.  You can get pork, chorizo, tripe or tongue  – but no chicken!  Puerco is my favorite -- they pull a good handful off that nicely roasted pork butt and plop it in the middle of the tortilla.  The rest is up to you.  Pull up a stool.  Lay on the salsa and the pico de gallo.  Squirt on a bit of lime.  But alas, no lettuce or tomato.  Sour cream?  What’s that?  You can top it with sliced radishes, onions, cucumbers, or cilantro (if you’re at a fancy stand).  Now bite in – and enjoy a real taco, Mexican style.  80 cents apiece.  Want a cerveza?