Preheat the oven to 100 degrees Celsius (fan) and line one large baking tray with greaseproof paper
Put the egg whites and white wine vinegar into a clean ceramic or metal bowl, using a stand mixer whisk at a medium speed until soft peaks start to form
Add a tablespoon of sieved caster sugar at a time, waiting 15 seconds before adding another spoonful. Continue adding the sugar, increasing the speed to high. Once the sugar has been added, whisk at a high speed for 8 minutes until thick and glossy
Sieve the cornflour and gently whisk for 15 seconds to incorporate into the mixture
Using a piping bag and pretty tip (I used Wilton 1M) Pipe rosettes or swirls onto a tray. I piped my swirls quite large, with a 11cm diameter
Bake for 30 minutes, then remove from the oven and allow to cool on the tray
