- Put the water, granulated sweetener and lemon juice in a small pan over a low heat until the liquid has reduced and begins to look sticky.
- Meanwhile, put the egg whites and cream of tartar in a bowl, and slowly whisk together until they form soft peaks.
- Slowly pour the sweetener mixture into the beaten egg whites.
- Gently add the cornflour and continue to mix until the egg whites are stiff.
- On a parchment-lined baking tray, spread or pipe the meringue to form a bowl, about 20-25cm (10 ins) across.
- Bake in a cool oven, 100°C/gas ¼ for about 1 hour 20 minutes, until it is firm and just beginning to colour. Open the oven door and leave the meringue in the oven until it is cool.
- When cool, carefully place the meringue on your serving plate.
- Combine a third of the fruit with the yogurt, adding sweetener if needed. Pile into the meringue and top with the remaining berries and a few sprigs of mint.
- If your meringue starts to brown before it is cooked, open the oven door for a few minutes to reduce the heat.
- Don’t fill your meringue until just before serving – it will go soggy if it’s left too long with the berry filling. However, you can make the yogurt/fruit mixture in advance and refrigerate until needed.