Summer berry pavlova roulade

Method

1. Heat the oven to 160°C/140°C fan/gas 3. Put the egg whites and cream of tartar in a large, spotlessly clean mixing bowl and whisk with an electric hand-mixer until they hold stiff peaks when the beaters are removed. Add the caster sugar, 1-2 tbsp at a time, whisking back to stiff peaks between each addition. Whisk in the cornflour and vinegar.
2. Spoon the meringue into the prepared tin and gently level out using a spatula. Bake for 20-25 minutes, then remove and cool for 10 minutes in the tin. Dust a piece of non-stick baking paper (roughly the same size as the tray) with icing sugar, then carefully invert the meringue onto it. Peel off the original baking paper and cool completely.
3. Meanwhile, whizz the blueberries, blackberries and 30g of the raspberries to a paste in a food processor, then push through a sieve into a jug (discard the solids).
4. Put the yogurt, zest and vanilla in a bowl and mix with a metal spoon. Trickle three quarters of the berry juices over the yogurt mix and scatter with most of the mint, then fold in to create a ripple effect.
5. Cut the rest of the raspberries in half.
6. Cut a groove along a short side of the meringue, about 2cm from the end – don’t cut all the way through. Spread the yogurt mix over the meringue, then scatter with half the raspberries, lightly pressing them in. Using the baking paper to help you, roll up the roulade from the indented edge. Still using the paper, lift the roulade, seam-side down, onto a serving plate. Remove the paper, top with extra berries and the remaining raspberries, drizzle with the rest of the berry juices and sprinkle with the remaining mint.