Line and grease a Swiss roll tin.
Sift flour, salt and baking-powder. Beat eggs and sugar in a bowl over a pan of hot water till thick and pale in colour. Do not let the bottom of the bowl touch the water. Lightly fold in flour, etc., and add the vanilla essence. Spread on the tin and bake in a hot oven (425° F., Gas 7). Quick cooking is essential to keep the roll moist. S