Brisket sits on the pit at Miller’s Smokehouse Every now and then you hit the motherlode on the Texas BBQ trail. For every 20 mediocre BBQ joints, there’s one good one. For every 50 good ones, there’s one great one. You can add Miller’s Smokehouse in Belton to the list of great ones. We first caught wind of Miller’s last week during BBQ Snob Daniel Vaughn’s trip to south Texas. Miller’s has been overshadowed in Belton by the better known Schoepf’s BBQ, which I have always heard is average fare. Daniel, who is knee deep in his book project on the…