Lunch rush at Smitty's Market, Lockhart, Texas, 2009. (Photo ©Darren Carroll) Our first installment of Focus on BBQ features photos shot by Austin photographer Darren Carroll. This launches an occasional series that will showcase great barbecue images shot by top photographers in the country. Most are friends of the Posse, which was founded in 2009 by a core group of writers & photographers at The Dallas Morning News. Over the years, we've had a number of contributing shooters, ranging from top commercial, news and sports photographers, including several Pulitzer Prize winners. Darren has an impressive mix of editorial and advertising clients. You might know his work from…