Preheat the oven to gas 1/2 (half) / 120C / 250°F and line a baking sheet with baking paper
In a small bowl whisk together the icing sugar, xanthan gum and 1 tsp of soya protein. Set aside
In a large bowl place the water, vinegar, vanilla and the 1 & 1/2 tsps soya protein. Whisk on high speed for up to 10 minutes until it has increased considerably in size, and is fluffy and bubbly
Keeping the whisk on high, add the icing sugar mix, 1 tbsp at a time. The mixture should eventually turn pure white and leave stiff peaks when the whisk is lifted out of the mix - the peaks are not quite as stiff as one would expect from an egg-based meringue
Pipe or spoon the mix onto the lined baking sheet. Put in the oven for 1 - 1.5 hours, until the meringues are totally set and easily peeled off the paper
Remove from oven, let cool and store in an airtight container
I'll keep trying for a soy-free alternative!