If you skipped the Edible Brookyn Cookbook sale and signing at Union Square Greenmarket today (that’s us below) no worries: The book’ll be back at Manhattan’s biggest market next month. (You can also score a signed copy at the Barnes & Noble tomorrow night in Park Slope, Brooklyn, or on Saturday at Brooklyn’s Grand Army Plaza Greenmarket.) But you also missed the cauliflower wizardry of market manager David Sherman. He’s there every Monday and Wednesday, and when some famous chef or cookbook author isn’t cooking for shoppers, he is. In the course of three hours we watched Sherman saute up three sessions worth of powerfully purple and sunny yellow-gold cauliflower with red peppers, purple onion, fresh thyme, a little cider vinegar and a shake or two of market-sourced paprika. Pretty awesome, and easy to do, too. Impressive! Plus, as Sherman told the crowd, those colors are no new-fangled invention: Cauliflower, potatoes and carrots all originally came in shades of purple — and thanks to Greenmarket farmers going back to older, tastier heirloom varieties they do again. And thanks to David Sherman, today you got to taste them.