A portrait of the late Bobby Mueller, shot by daughter LeAnn, watches over La Barbecue. (Photo by Tom Fox/DMN) Follow the roots of most of the joints on our recent Best of Austin tour and they trace back, directly or indirectly, to Texas legend Louie Mueller and his place in Taylor. LeAnn and John Mueller,  grand children of Louie and children of Bobby, are the most direct links. LeAnn owns La Barbecue. John is the pitmaster at John Mueller Meat Co. They used to work together but then there was that infamous blow up. Aaron Franklin, owner of Franklin Barbecue,…