Call it a New England summer staple. Call it shucked meat on buttered toast. But don't call it a lobster roll. Louis Mastrangelo believes his perfectly cooked. no-nonsense salad deserves a better base than a scrawny split-top bun, so he piles the low-mayo mixture between scali bread and dubs it a sandwich. The result- plus the kitschy crustacean decor around the picnic tables- makes it the quirkiest, and tastiest, version around.