Ladyfingers (savoiardi)

Makes about 25 5-inch or 32 4-inch ladyfingers. Preheat oven to 325 degrees F. Prepare your cookie sheets with shortening and flour as you would a cake pan. Set aside. Sift your flour and salt together, and then set aside. I like to sift mine three times. Adjust two racks to divide the oven into thirds, and preheat oven to 325 degrees F. In an electric mixer, beat your egg yolks, 1/2 of your sugar and vanilla until mixture is pale yellow. The mixture will be very light in texture, and the volume seems to triple. Transfer to another large mixing bowl. Wash your mixer bowl and beaters thoroughly with hot water and soap, rinse, then wipe bowl and beaters with vinegar which will cut any remaining traces of egg yolk. Rinse again with hot water and then dry. Pour in your egg whites, and whip on low until frothy. Add your cream of tartar. Increase the speed of the mixer to medium-high and beat until soft peaks begin to form. Now add your remaining half of sugar and beat until whites are stiff and shiny. You can tell it is ready if you turn your mixer bowl upside down, and the whites do not fall out. Briskly folk in about 1/3 of the whites to your mixing bowl with egg yolks/sugar mixture to lighten. Gently fold in the rest of your whites until just combined, and then sift flour over egg mixture and gently fold until combined. Your sponge batter will appear like soft clouds. Fill a large pastry bag with a large plain tip (about a #6) with your sponge batter. Working quickly, pipe 4-inch long, about 1/2-inch wide strips to your prepared cookie sheets leaving about an inch between savoiardi. It's allright if you pipe them a little closer. Gently dust your savoiardi by sifting powdered sugar over them. Put your cookie sheets in the oven. The savoiardi should be baked for about 15 minutes, but at the halfway mark, I reverse my sheets from front to back, top to bottom oven rack and then bake until they are turning brown and springy to the touch.