Tips found in monster size professional pastry chef cookbook and here is the key for making lady finger.
- sponge need to use biscuit (separate eggs) cold method
- make sure even yolks portion is batten to pale yellow (not just mixing)
- use slightly more flour comparing other sponge cake
- stiff peak for whites (can add a few drops of lemon or use cream of tartar) to make white hold its shape
- AIR is you friend and the key success!!
Verified the above tips really work. Picture proof. Check out my complete step by step instruction from here too.