Create the perfect pavlova.
Preheat the oven to 130°C (110°C fan) mark 1⁄2. Line a baking sheet with non-stick parchment paper and draw a 23cm/9” circle, turn the paper over.
Put the egg whites into a large clean bowl and whisk until stiff. Gradually add two-thirds of the sugar a tablespoonful at a time, whisking between each addition. Mix the cornflour into the remaining third of sugar and add to the egg white mix, whisking until stiff and glossy. Carefully fold in the vanilla and vinegar.
Scoop the meringue onto the paper and push the meringue out to fill in the circle, creating a dip in the middle, flick the meringue into peaks or swirls around the edge.
Bake in the oven for 1 1⁄4 hours or until firm and crisp around the edges. Remove from the oven and leave to cool. The meringue may very well crack and sink a little, transfer to a flat serving plate (the meringue may very well crack and sink a little) .
While the meringue is cooking, put the berries into a pan with 3 tablespoon water and gently bring to simmer, cook for 1-2 minutes until the juice just begins to run from the fruit and colour the juices.
Add the undiluted Ribena to the berry mixture.
Blend the castor sugar with 2 teaspoons of water, add to the pan and simmer until the juices have thickened. Turn berries into a bowl to cool.
When ready to assemble, whip the cream until softly peaking, fold in the crème fraiche then add half of the berries and fold about four times to create a swirled effect. Pile this onto the pavlova, gently spreading it to the edge then spoon over the remaining berries and syrup.