When the weather allows, a guy in a truck can be spotted picking leaves off a sprig of fresh tarragon, readying it for a lobster roll, just down the block from the party scene outside the The Fine Line. The vehicle, Smack Shack, which is parked in a surface lot a First Ave. and Fourth St. N., is the brainchild of Josh Thoma, best known for his with Tim McKee at La Belle Vie, Solera, and Smalley's Caribbean Barbeque. The seafood at Smack Shack tastes so fresh that you might mistake the sound of the truck's humming generator for the ocean's lapping waves. Those with a bit of gustatory gumption should order the King Roll: a good half-pound of fat lobster hunks--sweet, pink-speckled meat that's studded with crisp bits of cucumber and celery, laced with ocean brine, and dribbling a seasoned mayo. The lobster overflows its edible pocket: a buttery hunk of griddled Texas Toast that's sliced like a bun to help prevent spills. The King rivals those sold at East Coast fish shacks for upwards of 20, but costs just 13-and-a-half smacks (the smaller roll costs $8.50). Are these guys trying to lose money?