CALL it the theater lover’s answer to Restaurant Week – a chance to sample the cream (both fresh and curdled) of off-Broadway at a rock-bottom price: $20 a ticket.

The catch? You’ve gotta get to the box office 20 minutes before showtime and be prepared to pay cash. Introducing “20at20,” which starts Sunday and runs through March 11.

Participating shows include the critically acclaimed “The Voysey Inheritance,” “Gutenberg! The Musical!” and “25 Questions for a Jewish Mother a couple of spectacles (“The Gazillion Bubble Show” and the not-yet-opened “BE” by Mayumana); several hardy perennials (“Stomp,” “Altar Boyz”) and that moldy chestnut, “Perfect Crime.”

Tickets are subject to availability. Check offbroadway.com for a complete list of shows and venues.