From the book "Mad Hungry," by Lucinda Scala Quinn (Artisan Books).
Heat an ovenproof platter in a warm (200 degrees Fahrenheit) oven.
Place the flour, salt, baking powder, eggs, milk, water, and vanilla in a blender and blend until completely combined and the consistency of heavy cream. The batter can be refrigerated up to 1 day in advance.
Heat a well-seasoned 6-inch skillet or crepe pan until very hot to the touch but not smoking. Swirl around enough butter to coat the pan. Gently and slowly pour a 3- or 4-tablespoon portion of batter, immediately swirling to cover the entire bottom of the pan in as thin a layer as possible. When the edges begin to turn golden and pull away from the pan, use a spatula to lift and flip the crepe. Cook until it is just set, about 30 seconds. Repeat until the batter is finished, stacking the crepes on the platter in the oven as you go. Serve immediately with some butter, sugar, and a squeeze of citrus.
If prepared in advance, the batter will keep well in the refrigerator overnight. Or, for the finished crepes, wrap them tightly in plastic wrap -- they will hold in the refrigerator for 2 or 3 days.