The old saw is true that “there’s no such thing as a free lunch.” But at least for today, the money you spend can go to a good cause. As part of their opening festivities, Roti Mediterranean Grill (1747 Pennsylvania Ave. NW) is giving away free lunches, but requesting donations be made to D.C. Central Kitchen. The non-profit trains formerly homeless men and women how to cook, using donated surplus food to feed other hungry individuals, as well as providing catering services to some local charter schools. The Roti promotion runs from 11 a.m. to 2 p.m., and includes a sandwich, salad or Mediterranean plate plus fountain beverage. Rules stipulate that you must be in line by 2 p.m. to take advantage of the deal.