Preheat the oven to 190°C / 375°F / Gas mark 5.
Line a 33 x 23 cm Swiss roll tin or roasting tin measured across the base with a large sheet of greaseproof paper, snipping diagonally into the corners of the paper then pressing into the tin so that the base and sides are lined.
Whisk the egg whites in a large bowl until stiff peaks form.
Gradually whisk in the sugar a teaspoonful at a time then continue to whisk until thick.
Mix the cornflour and vinegar together then fold into the egg mixture.
Spoon the meringue onto the paper lined tin and bake for 10 minutes until well risen and just beginning to colour then reduce the heat to 160°C / 325°F / Gas mark 3 and cook for 5 minutes or until just firm to the touch and starting to break and crack.
Place a tea cloth on to a work surface, cover with a sheet of greaseproof paper and sprinkle with a little extra sugar.
Invert the hot meringue on to the paper, remove the tin and leave to cool for 1-2 hours.
Once cooled, peel off the lining paper from the meringue.
Whip the cream until it forms soft swirls then spoon over the meringue.
Spoon the lemon curd on top then sprinkle with the berries.
Roll up the meringue, starting with the narrowest edges, using the paper and tea cloth to help.
Carefully transfer to a serving plate and remove the paper and tea cloth.
Serve cut into thick slices with extra berries and mint garnish.