Preheat oven to 350°F and line 2 baking sheets with parchment paper.
Place egg whites in a large mixing bowl and whip until soft peaks. Continue whipping and add in ¼ cup of sugar, 1 tablespoon at a time. Whip until stiff peaks.
In a separate medium bowl, beat egg yolks, the remaining sugar, vanilla and salt. The yolks will increase in volume and they will become lighter in colour. Pour the egg yolks mixture over top of the egg whites. Sift flour and cornstarch over top. Use a spatula and gently fold the ingredients together. Be careful to not deflate the egg whites.
Transfer the batter into a pastry bag and pipe batter into 4" lines on a parchment lined baking sheet, 2" apart. Bake at 350°F for 15-18 minutes, or until cookies are lightly golden.
Allow them to cool on a wire rack and then dust with confectioner's sugar. Store in an airtight container. If you are using them for tiramisu, leave them out, uncovered and at room temperature, they day before you need them.
Make sure the eggs are at room temperature so they will whip up easily.
Carefully fold the ingredients together so the egg whites don't deflate.
Pipe out batter using a ½" piping tip (I used Ateco #806), or snip a ½" off a corner of a zip lock bag (to use as a pastry bag substitution).
These make enough lady fingers for a 9x9" tiramisu. If you would like to made a tiramisu in a 9x13" baking dish, double the recipe.