BBQ Snob Daniel Vaughn served a nice steak taco at Hot Luck Austin. Hot Luck Austin, the new food festival, officially opened Thursday night at Franklin Barbecue, near downtown. With the State Capitol building visible, the joint’s “back yard” is a great spot for a party. As normal, though, when Posse member Mike Gagne and I arrived a few minutes before the 6 p.m. start, there was a line. We were 40 or so back. But it moved quickly and there was never much backup at the seven chef stations over the next three hours. The event was open only…