Preheat your oven to 350 F (175 C) degrees, then lightly brush 2 baking sheets with oil or softened butter and line with parchment paper.
Beat the egg whites using a hand held electric mixer until stiff peaks form. Gradually add granulate sugar and continue beating until the egg whites become stiff again, glossy and smooth.
In a small bowl, beat the egg yolks lightly with a fork and fold them into the meringue, using a wooden spoon. Sift the flour over this mixture and fold gently until just mixed. It is important to fold very gently and not overdo the folding. Otherwise the batter would deflate and lose volume resulting in ladyfingers which are flat and not spongy.
Fit a pastry bag with a plain tip (or just snip the end off; you could also use a Ziploc bag) and fill with the batter. Pipe the batter into 5" long and 3/4" wide strips leaving about 1" space in between the strips.
Sprinkle half the confectioner's sugar over the ladyfingers and wait for 5 minutes. The sugar will pearl or look wet and glisten. Now sprinkle the remaining sugar. This helps to give the ladyfingers their characteristic crispness.
Hold the parchment paper in place with your thumb and lift one side of the baking sheet and gently tap it on the work surface to remove excess sprinkled sugar.
Bake the ladyfingers for 10 minutes, then rotate the sheets and bake for another 5 minutes or so until the puff up, turn lightly golden brown and are still soft.
Allow them to cool slightly on the sheets for about 5 minutes and then remove the ladyfingers from the baking sheet with a metal spatula while still hot, and cool on a rack.
Store them in an airtight container till required. They should keep for 2 to 3 weeks.