Ingredients

Method

For the mousse:
• 450 g strawberries, stems removed and halved
• 2½ t fresh lemon juice
• 75 g sugar
• 1 T Kosher gelatine
• ½ cup whipping cream
• For the sponge:
• 6 large free-range eggs, separated
• 100 g sugar
• 1 t vanilla extract
• 55 g potato starch
• 30 g raw shelled pistachios, ground
• 2 T icing sugar, plus extra for dusting
• 1 T matcha (optional)

Method

Ingredients

1. To make the mousse, purée the strawberries until smooth using a blender or food processor.

2. Transfer to a small saucepan, add the lemon juice and sugar and cook over a medium-low heat for 5 minutes, stirring occasionally, until the sugar is completely dissolved. Whisk in the gelatine and remove from the heat once it has dissolved.

3. Strain the mixture through a fine-mesh sieve into a bowl, pressing quite hard to get as much purée as possible. Cover the purée and chill for 10 minutes.

4. Remove from the fridge and whisk, then chill for a further 10 minutes.

5. Whip the cream until stiff peaks form. Remove the strawberry purée from the fridge and slowly fold into the whipped cream, a little at a time. Chill the mousse for at least 3 hours, or overnight if making in advance.

6. To make the sponge, preheat the oven to 190°C and trim a piece of baking paper to fit perfectly into the bottom of a 30 x 40 cm baking tray (a jelly roll pan is ideal). In a large mixing bowl, whisk the egg yolks and sugar until well combined. Add the vanilla and potato starch and whisk well. Set aside.

7. In a large mixing bowl, beat the egg whites with an electric whisk or mixer at a medium speed until foamy. Add the lemon juice and increase the speed to high. Beat until stiff peaks form. Fold a third of the egg whites into the egg yolk mixture until well combined. Add this mixture to the remaining egg whites and mix at a low speed until combined. Add the ground pistachios and matcha, if using, and mix gently.

8. Pour the batter into the baking sheet and use an offset spatula to spread evenly. Bake for 15 minutes, or until the top of the sponge is lightly browned and it springs back when pressed gently. While the cake is in the oven, use a sieve to dust a clean tea towel with icing sugar.

9. Take the cake out of the oven and immediately run a knife along the edges to loosen it from the pan. Place a sheet of baking paper over the top of the cake, cover with a cooling rack and flip the pan and cooling rack over. Lift off the pan and peel the baking paper off the bottom of the sponge.

10. Using the baking paper between the cake and the cooling rack, lift the cake and flip it onto the dish towel. Remove the baking paper, then roll up the cake tightly in the towel, starting from the short side of the cake. Make sure the seam of the roll is at the bottom. Set aside until cool to the touch, about 20 minutes.

11. To assemble, unroll the cake and remove the towel. Remove the mousse from the fridge and stir to soften. Use an offset spatula to spread the mousse evenly over the cake, right up to the edges. Roll up the cake.

12. With the seam at the bottom, lift the roll and place it on a sheet of plastic wrap, then tightly wrap it in more plastic wrap. Place on a baking sheet and freeze for at least 6 hours or overnight. To serve, remove from the freezer and trim the ends to neaten the edges (eat those!). Slice the roll into roughly 2½ cm slices and plate. Allow to thaw slightly before serving.

Find more cake recipes here. 

Photograph: Jan Ras
Production: Bianca Strydom
Food assistant: Raymand Buitendag