Preheat the oven to 180°C.
Whisk egg whites to stiff peaks and gradually add caster sugar until glossy.
Gently fold in the vinegar and chopped pistachios.
Line a tray with greaseproof paper and place a 7cm chefs' ring on top.
Spoon mixture into the ring to create 6-8 mounds, leaving space between each.
Place in oven, reduce heat to 150°C, and bake for 45 minutes.
Whisk double cream with vanilla seeds and sugar until stiff peaks form.
Gently fold the Greek yogurt into the cream mixture.
Melt butter with honey in a pan and bring to a boil.
Stir in orange juice, zest, and 300g of blueberries to coat.
Place a meringue on a plate, top with cream and warm blueberries.
Garnish with the remaining uncooked blueberries and serve.