Jim Lahey is opening a new branch of Sullivan Street Bakery.There we were at the second Monday Night Movie Night at NYC's Co. pizza, watching Les Blank’s 31-minute Yum Yum Yum!, an ode to everything Cajun (in the fun film: lots of music, lots of cooking and a youngish Paul Prudhomme). We were also sampling a Cajun menu inspired by the movie, including superb beef-tongue toasts (you see some major beef tongue in Yum Yum Yum!) and spicy andouille-and-cockle pizza with green-pepper puree and Gruyère (no pizza in the movie, but there is graphic sausage-making). And then, there we were getting a tour of what will be an outpost of the excellent Sullivan Street Bakery, a door or two up from Co. on Ninth Avenue. (What with the expansion of Txikito down the block, this could become the best block to eat in the city.) Jim Lahey, the genius baker and co-owner of both Sullivan Street and Co., has taken over a bakery that once produced cheap cakes (and still carries the pervasive sweet smell of bad buttercream). Hopefully he'll be baking bread there by Halloween, as well as introducing a snack that will be even more addictive than Sullivan Street's pizza bianca.