For the glacé beetroot, put the sugar, ginger and ½ cup (125 ml) water into a small saucepan. Stir until the sugar dissolves, then bring to the boil. Add the beetroot and boil for 30 minutes, or until only a few tablespoons of syrup are left in the pan. Gently toss the blackberries and orange segments through, squeeze in any juice from the orange membranes, then leave to cool. This will keep in an airtight container in the fridge for a day or two; remove the ginger before serving.
Before starting on the veringues, make sure your mixing bowl is scrupulously clean by swishing some white vinegar on a clean tea towel or paper towel and wiping out the bowl to remove any traces of fat, which will stop the aquafaba foaming properly. Also make sure your beaters are scrupulously clean.
Using a stand mixer with the balloon whisk attachment, or a hand-held beater and a large metal bowl, beat the aquafaba on medium–high speed until the volume doubles and soft peaks form, which will take about 5–10 minutes (depending on your beaters).
Start whisking in the sugar one tablespoon at a time until it is all used up, whisking for another 5–10 minutes until the veringue is like glossy cumulus clouds, with no feeling of sugar-granule grittiness when rubbed between your fingertips, and tasting like marshmallow. Mix in the vanilla.
If not using the veringue mixture immediately, detach the whisk and leave it in the mixing bowl with the whipped aquafaba, cover with plastic wrap and leave in the fridge for no more than a few hours. When ready to serve, reattach the whisk and whisk for another 5 minutes to reinvigorate the veringue. It’ll fluff back up good as new.
To serve, spoon the veringue mixture onto plates. If you like, use a kitchen blowtorch to kiss the tips of the veringue and singe slightly. Spoon your chosen yoghurt or cream alongside and top with the glacé beetroot and blackberries; the syrup will delightfully stain the cream. Garnish with the pistachios and sorrel leaves and serve.