Step 1 Preheat oven to 130ºC. Line a baking tray with grease-proof paper.

Step 2 Place egg whites in a large glass bowl and leave to come to room temperature. Whisk on a low speed. Gradually increase speed until frothy. Continue whisking until whites are stiff and form peaks.

Step 3 Whisk in a third of the sugar at a time. Make sure it is well mixed before adding more.

Step 4 Use a metal spoon to fold in cornflour, vinegar and vanilla essence. Spoon meringue onto prepared baking tray. Shape into a 23cm round, making a hollow in the centre.

Step 5 Bake for 1 1/4 to 1 1/2 hours, until meringue is firm and crisp on the outside. Cool thoroughly before removing greaseproof paper. Cool before filling. For the filling, slice strawberries. In a bowl, mix blackcurrants with yoghurt. Spoon into centre of meringue. Add strawberries and chill for 20 minutes. Serve decorated with fresh mint.