From October through May every year, Sundays are steakhouse night at Cambridge restaurant Puritan & Co. More specifically, it’s Prime Rib Sunday, when chef Will Gilson’s team takes on everybody’s favorite roast. The seasonal, weekly prime rib at Puritan includes a 10-ounce slice of rosy pink beef au jus with your choice of steakhouse side, plus an ice cream sundae for dessert. Want to visit the farm-to-Inman Square spot some Sunday with friends who’d prefer a nice salad? Full table participation on Prime Rib Sunday isn’t required, but reservations are encouraged.