Heat oven to 150C/130C fan/gas 2.
Using a pencil, mark out the circumference of a dinner plate on baking parchment.
Whisk 4 egg whites with a hand mixer until they form stiff peaks, then whisk in 250g caster sugar, 1 tbsp at a time, until the meringue looks glossy.

Whisk in 1 tsp white vinegar, 1 tsp cornflour and 1 tsp vanilla extract.
Spread the meringue inside the circle, creating a crater by making the sides a little higher than the middle.

Bake for 1 hr, then turn off the heat and let the Pavlova cool completely inside the oven.
When the meringue is cool, take a pan and add chopped 100g of the hulled strawberries. Mix them with 100g of the raspberries and 2 tbsp icing sugar and turn the gas on stir about 1 /1/2 minute turn off flame and cool down all fruit mixture completely.

Whip 350ml double cream with the remaining 1 tbsp icing sugar and spread it over the meringue. Put the all fruit mixture on the cream and finally pour the sauce over the whole lot.