Potato meal, three ounces.
Sugar, six ounces.
Beat well the egg-yolks with the sugar, add the potato meal and the lemon juice and stir everything for half an hour.
Finally beat well the whites, and mix the rest, stirring continually but slowly. Pour the mixture in a smooth and round mold, greased with butter and sprinkled with powdered sugar. Put at once in the oven.
Remove from the mold when cold and dust with powdered sugar and vanilla.