With the rack in the middle position, preheat the oven to 190 °C (375 °F). Line a 43 x 30 cm (17 x 12-inch) baking sheet with parchment paper, letting it hang over both sides. Generously butter the paper and sides.
In a bowl, combine the flour and icing sugar.
In another bowl, beat the eggs, sugar and vanilla with an electric mixer until frothy, triples in volume and forms a ribbon off the beaters, about 10 minutes.
Sift the dry ingredients over the egg mixture folding gently while sifting, using a spatula or a whisk.
Spread the batter on the baking sheet. Bake for about 10 minutes or until a toothpick inserted in the centre of the cake comes out clean. Flip over parchment paper and cover with a clean cloth. Let cool to room temperature.
Spread the rhubarb compote over the cooled cake. Roll the cake from the short side and place on a serving dish. Refrigerate for 1 hour or until ready to serve.
In a bowl, combine the icing sugar and lemon juice. Pour over the cake.