To make the meringue, take a large bowl and whip up the egg whites to stiff peaks. Add in the caster sugar, a tablespoonful at a time, mixing well after each addition till you have a thick, glossy meringue. Finally mix in the vanilla essence, corn flour and vinegar. Take a large baking sheet and cover with baking paper. Put a dinner plate on top and draw around it so that you have a circle drawn on the baking paper. Spread the meringue mixture into the circle, making the outer edge thicker than the center. Place the meringue the oven at 140`c, on the middle shelf and bake for 40 minutes. When ready, turn off the heat and leave in the meringue in the oven until completely cold. Meanwhile, take 200g of the strawberries and place into a food processor with 1 tablespoon of the icing sugar, and pulse to a smooth sauce. Pass the mixture through a sieve to remove the seeds and pieces and discard. Put the strawberry sauce to one side while you whip the cream with the remaining icing sugar to stiff peaks. Take the cooled meringue, and place it on a large serving plate. Spread the whipped cream into the center of the meringue and place the remaining strawberries all over the top, side by side to cover the cream. Chill the strawberry pavlova for at least 30 minutes. Just before serving the summer strawberry Pavlova, drizzle the strawberry sauce over the top of the strawberries.