For the strawberry filling:
1. Put about a third of the strawberries in a blender or food processor with the granulated sugar and blitz well. Transfer to a bowl and add the Marsala or orange juice. Stir in the remaining strawberries and place in the fridge.
2. The flavour gets better the longer you leave it, so do this a few hours ahead if you can, though if you are ready to go now then a minimum of 30 minutes is fine.
3. Preheat the oven to 190°C, Gas Mark 5. Grease a 23 x 33cm Swiss roll tin or small roasting tin and line with baking paper.
For the sponge:
1. Put the eggs, sugar and vanilla in a large bowl and beat with an electric whisk until the mixture is very pale yellow, foamy and mousse-like. Fold in the warm water with a large metal spoon. This helps prevent the Swiss roll from cracking when you roll it later.
2. Sift over the flour and salt and fold in gently with the metal spoon. Don't overmix here or you will knock out the air and the Swiss roll will lose its sponginess. The trick is to incorporate all the flour with as few 'folds' as possible.
3. Pour the mixture into the prepared tin and level it gently with a palette knife or the back of a large spoon. Bake in the oven for 10-15 minutes, or until it has shrunk a little from the sides of the tin and feels springy to the touch. Remove from the oven and turn the cake out onto a sheet of baking paper sprinkled with caster sugar.
4. Leave for 10 minutes, then gently peel the lining paper off the sponge and leave to cool completely.
5. In a large bowl, gently mix together all the ingredients for the mascarpone cream until smooth.
6. To assemble the cake, trim off any rough edges of the sponge with a sharp serrated knife if necessary to get the sides nice and tidy, then spread the mascarpone cream all over the sponge, leaving a small margin so it does not squelch out when it is rolled.
7. Spoon the macerated strawberries out of the puree and scatter over the rest of the mascarpone filling. Drizzle a third of the strawberry puree over it as well (reserving the rest).
8. With the shortest side facing you, begin to roll up the sponge (away from you) using the baking paper to help. Try to do it as tightly as you can for an impressive-looking finish. Once you have rolled it all up, make sure the join is underneath so it does not come undone. Carefully lift onto a serving plate. You can do this with your hands or use two fish slices or spatulas.
9. Sprinkle with some caster sugar and decorate with extra sliced strawberries. Serve in slices with the remaining strawberry sauce drizzled over. Best on a hot summer's day with some fresh lemonade.
Recipe courtesy of Lorraine Pascale, Baking Made Easy HarperCollins, 2012 (£20)