Wicked pahking laht bahbecue?
I've never even visited Boston, but it seems to me that chowder would be a good one. And something in the North End. I would assume Ming Tsai would stop by. You could maybe have them do a riff on ball park food, honoring Fenway as the oldest park in the majors?And what about whoopie pies? I don't know that they're absolutely Bostonian, but they're a New England thing, and dessert challenges, always hilarious.
Cooking at Durgin Park (where hey, surly service is expected, so front-of-house could be interesting.) A quickfire with baked beans. A seafood shack, with clam bellies, lobster rolls, etc. (New England rather than Boston-specific.) They've done ballpark cooking before, but they definitely should have some Red Sox event. Maybe while the chefs are wearing beards.
Gotta do lobster roll. My friend from Massachusetts, who now lives in Seattle, always binges on the lobster rolls when she goes back to MA for visits.
Lobster roll is assuredly an iconic Boston/NE food item, but it's hard to do much in the way of a challenge built around it, since it's so simple. Maybe a Quickfire.