We had the rare opportunity to try a new BBQ joint on its second day of operation today. Plans were set into motion when Texas BBQ Posse member Gary Barber spotted a big smoker at the corner of Commerce and Walton Streets while at lunch in Deep Ellum the day before. Ernest and Francine Williams opened Mama Faye’s BBQ at 2933 Commerce on Thursday. The joint is named after Francine’s mother Faye, who supplied the sauce recipe, a family secret that dates back to the 1900s. They are already known in Deep Ellum for their mobile operation, selling sandwiches in…