Sportello, Barbara Lynch’s casual Italian eatery in Fort Point Channel, is going rogue. Though it's not officially participating in Restaurant Week, it is offering a special three-course prix fixe dinner menu March 17-22 and March 24-29, for $29 per person, with a three-course lunch menu offered at $20.13. Among the offerings at dinner: fettuccine with crab, lemon and jalapeño, and Atlantic halibut with green garlic and mussels. Need more suggestions for Restaurant Week? Scope out our list of reservations to make now (617-737-1234).