Most New England transplants have probably long given up on the prospect of getting a decent lobster roll in the Bay Area, and have had to settle for local Dungeness crab — itself a great delicacy, but a different breed of crustacean entirely. The lobster that is available tends to be overpriced and, given the long distance it has to travel, not very fresh-tasting — a fact most vendors try to mask by drowning the meat in pools of sauce. Who would have guessed that the closest thing you can get to an authentic Maine lobster roll gets around these challenges simply by not using lobster at all? Yes, Picán’s Louisiana crawfish roll (available only in season and during lunch hours) is the real deal: buttery, griddled split-top bun; crunchy cucumbers; and — to give the sandwich a Southern slant — a generous slather of Duke’s Mayonnaise. Of course, the most important component is the mound of sweet crawfish meat that’s just about good enough to make you forget about Maine.