Hiding behind the façade of tattered sign awaits Mamoun’s Falafel, which serves one of the cheapest meals in New York City — and a falafel sandwich that’s firmly entrenched in this town’s food zeitgeist. Whether you hit the location on MacDougal Street off of Washington Square Park or the outlet on St. Marks Place, the digs aren’t fancy — space is slightly claustrophobic, and the dingy booths are always sticky. But for around $10, you can get a three-course meal. Start with a side of zippy tabbouleh for $3. Move into that sandwich — crunchy falafel tucked into a nest of warm pita and slathered with creamy hummus — for $4. Finish with a syrupy piece of knafe, the pistachio adaptation of baklava, for two bucks. This is your next cheap date, sorted.