Prepare a large pot of boiling water. Shuck the corn, then boil it for 8 minutes, until tender. Remove immediately.
Meanwhile, in a medium bowl mix together the tahini and lemon juice. If necessary, stir in 1/4 cup water or more to bring to a thick, spreadable consistency.
To serve, spread the corn with the tahini mixture, then drizzle with sriracha and sprinkle with cilantro. (Tip: Hold a finger over the nozzle of the sriracha bottle; it comes out fast!)