Lemon Roulade with Citrus Mousse

For the lemon roulade:

1. Preheat the oven to 220°c.

2. Line a 12" Swiss roll tin with parchment paper.

3. Combine the eggs and caster sugar and whisk over a double boiler until the mixture turns pale yellow. Keep the temperature of the water in the double boiler at an even low setting so that the eggs do not cook too fast.

4. Add flour and hot (but not boiling) water and fold together to make a smooth batter.

5. Stir in the zest.

6. Pour the batter into a prepared baking tin and bake for about 8-10 minutes until golden.

7. When done, remove from the tin, and peel off the baking paper lining.

8. Take another parchment paper and roll the sheet of sponge along with the paper to make a roll (roulade).

9. Wrap in a clean towel and leave aside to cool.

For the citrus mousse:

1. Beat the egg yolks and sugar together in a large mixing bowl until pale yellow.

2. Add the orange juice to this mixture and whisk in rapidly until the mixture is light and foamy.

3. In a bowl combine the gelatine and warm water. Leave it to bloom. Place this bowl over a saucepan of hot water and stir till the gelatine completely dissolves in the water.

4. Stir the gelatine mixture into the egg yolk mixture.

5. In a large mixing bowl, whip the topping till it has doubled in volume. Fold in the zest.

6. Whisk the egg whites till stiff and fold them in to make a smooth even mixture.

7. Leave the mousse in a cool place till it begins to set. Stir occasionally until it almost sets.

For the assembly:

1. Unroll the cooled sponge, remove the parchment paper, and spread the mousse over it. Carefully roll up the sponge again and transfer onto a serving plate with the edge of fold at the bottom.

2. Place in the refrigerator for 30-40 minutes for the mousse to set.

3. Cut 1 slices from the roulade, and serve cold.