Stir the vanilla bean and seeds into the sugar and 1/3 cup water in a small saucepan. Bring to a boil and cook for 3 minutes. Remove from the heat and cool completely.
In each of two 10-ounce glasses, stir together 1 1/2 tablespoons syrup and 1/2 cup milk. Fill the glass with seltzer. Give it a stir and taste it before adding all the seltzer -- you want to be sure it doesn't get too dilute.
Before starting Food52 with Merrill, I was a food writer and editor at the New York Times. I've written several books, including "Cooking for Mr. Latte" and "The Essential New York Times Cookbook." I played myself in "Julie & Julia" -- hope you didn't blink, or you may have missed the scene! I live in Brooklyn with my husband, Tad, and twins, Walker and Addison.