Preheat the oven to gas 4, 180°C, fan 160°C. For the meringue, put the egg whites in a large bowl and whisk into stiff peaks. Add 200g (7oz) of the sugar, a little at a time, and whisk for 3-5 minutes until stiff and glossy. Stir in the vinegar, cornflour and vanilla.
Line a baking sheet with nonstick baking paper. Draw a circle 23cm (9in) in diameter on the paper, using the base of a cake tin as a guide. Spoon the mixture inside the circle, then spread out, building up the sides a little. Put in the oven and immediately turn the heat down to gas 1, 140°C, fan 120°C and bake for 1 hour. Turn off the oven, leaving the door slightly ajar, and leave the meringue to cool in the oven. Once cool, the meringue base can be stored in an airtight container for up to 3 days.
Using a small sharp knife, trim the ends of the clementines and cut off the zest in strips, discarding the pith. Cut the clementine into segments. Put a couple of strips of zest in a pan. Add the wine, the remaining sugar and the cinnamon to the pan, and simmer on a low heat for 10 minutes to make a syrup, stirring to dissolve the sugar. Put the clementines in a bowl, pour over the warm syrup and leave to cool.
Just before serving, whip the cream into soft peaks. Pour the syrup through a fine sieve (put the clementines to one side). Stir a tablespoon of syrup through the cream. Put the meringue on a serving plate, swirl the cream over the meringue, then scatter over the reserved clementines and pomegranate seeds. Drizzle over more syrup to serve.