Austin pitmaster Mark Gabrick’s new BBQ sauce “Texas Tang.” Photo ©Gary Jacobson/Texas BBQ Posse First, an admission. Mark Gabrick is a friend. He has accompanied the Posse on some of its smoked meat sojourns. He’s good company and he knows barbecue. Gabrick also operated a food trailer in Austin until the Coronavirus Pandemic shut everything down in March. Now, with his regular business closed, he is making and selling barbecue sauce. His first offering: Texas Tang. We sampled some during a rib cook on July 4 and it got strong positive reviews from four Posse regulars. Keep in mind, these…