I had been meaning to check out the burger at Postrio, and I was already at The Venetian checking out the eternal twilight of Saint Mark's Square. This Wolfgang Puck establishment delivered the culinary equivalent of "bad touch" from mom's new boyfriend. I should have known that everything was going to go terribly wrong from the painful interaction with the server.. Me: What are the cuts of beef in the burger? She: Angus. Me: That is a type of cow. I am more interested in the parts of the cow that the meat comes from so that I can order my burger cooked to a temperature that is most appropriate. Can you please go check? She: *huff* Me: Am not trying to be a pain; I am trying to order the burger correctly so that I can properly review it. I assumed that she was new or fussy or just plain bad at her job. I failed to take this as an omen. The other clue was that the restaurant was all but empty in the middle of the bustling St. Mark's Square. Postrio was Italian slang for "crappy food and service." The beef was flavorful and beefy. Sadly, it was over-cooked and rubbery. The burger patty had the shape and texture of a fist. Beyond that, the burger was peppered with connective tissue. The burger's exterior tasted like an oniony salt. It was as if it had been dusted with cheap onion soup mix. The bun was stale and dry...really dry and stale. The bun was burned to the point of tasting like carbon. The bottom of the bun had black grill marks, which imparted a nasty bitterness directly to the tongue. The kitchen at Postrio phoned it in and subsequently dropped the ball. After I sent my meal back, there was no offer for a refire or a make-good of any sort. Apparently, that was their best effort. The manager, Luckas, agreed that the bun was burned and stale and that the burger was rubbery. I sent my plate back after a scant 3 bites.My son got through a third of his before he gave up due to the strong flavor of char. I was granted the "friends and family discount." Postrio only charged me $37 for that shameful mess. Jerks! Front and back of house were a well-oiled machine designed to lighten wallets and deliver awful food. Postrio earned the title of worst burger in Las Vegas. On the day that I visited, the quality of the burger and service was excremental, and that was being generous.