Madcapra, my friend Gillian insists, is not a falafel stand. And in several respects I may even agree. Its chefs, Sara Kramer and Sarah Hymanson, come to Madcapra from Glasserie, a well-regarded restaurant in a gloriously inconvenient corner of Brooklyn. When you find yourself at its marble counter on a Wednesday afternoon, you will find out more than you need to know about what was at the farmers market that morning, whose arugula is pungent and whose lollarossa lettuce is especially tender, and what citrus is two weeks past its peak. It may be located near where the Middle Eastern concession used to be in the Grand Central Market, but its nearest neighbor is devoted to artisanal cheese.