Stripy strawberry Swiss roll

1. Preheat the oven to 200°C/gas mark 6. Grease a 23cm x 33cm Swiss roll tin with a little sunflower oil, line with non-stick baking paper and grease again.
2. Whisk the sugar and eggs in a large bowl with an electric whisk for 8 to 10 minutes, until the mixture has doubled in size and is thick enough to hold a trail of mixture when the whisk is lifted. Sift half of the flour over and fold it in very gently until well combined. Sift and fold in the remaining flour the same way.
3. Spoon half of the sponge batter (about 200g) into a separate bowl. Add the gel food colour a little at a time to give your preferred colour, folding it in gently so as not to knock out too much air. Spoon each batter into a separate disposable piping bag and snip the tip of each one to make a 1cm opening.
4. Starting in one corner of the prepared tray and working on the diagonal, pipe a line of each colour. Continue to pipe alternate colours, with the lines getting longer as you work along the tray and then shorter again as they reach the other end. Once the whole tray is filled, go over the stripes again with any remaining batter.
5. Bake in the oven for 10 to 12 minutes, until golden, risen and springy to the touch. Allow to cool slightly in the tin.
6. Meanwhile, lay a lightly dampened clean tea towel on your work surface. Put a piece of baking parchment on top of the tea towel and dust it lightly with caster sugar.
7. Once the sponge is cool enough to handle, flip it out onto a clean surface beside the sugared paper. Carefully peel the paper away from the sponge base, then flip the sponge over onto the sugar. Using the tea towel to help you, roll up the sponge from one narrow end, keeping the paper inside to prevent it from sticking together. Leave to cool completely.
8. Meanwhile, trim all the strawberries. Reserve eight small strawberries (or eight halves if large) and finely chop the rest. Softly whip the cream in a large bowl and spoon 50g of it into a piping bag that has been fitted with a star nozzle. Gently fold the chopped strawberries into the remaining whipped cream.
9. When you’re ready to serve, unroll the sponge and spread the strawberry cream all over the surface. Roll it back up again and sit on a rectangular serving plate or board, seam side down. Pipe eight rosettes of cream all along the top of the Swiss roll and sit a reserved strawberry in each one. Decorate with fresh mint leaves if liked and serve.

Tip: Use raspberries instead of strawberries if preferred, crushing them lightly rather than chopping them for the filling mixture.