Twice a year, in Boston and other cities, local restaurants declare Restaurant Week. (Or as it's oddly called now here for some reason, Dine Out Boston.) Participating venues offer special menus at reduced prices. So it's a great time to visit places whose tabs might otherwise be prohibitive. To my mind, the best deal in town is lunch at Toscano in Harvard Square. Three courses, $20. First course this time around, a salad of roasted beets with Gorgonzola dolce and arugula. So, so good.