Preheat the oven to 140ºC. Put parchment paper on the baking tray.
With an electric whisk, beat the egg whites until they form soft peaks. The egg whites should be at room temperature. Add the sugar little by little and beat until they are finished. In this way, we obtain a firm and glossy meringue.
Add the lemon juice and the corn starch. Whisk lightly to mix.
Pour the mixture onto the baking tray and with the spatula give it a circular shape, leaving a shallow hole in the centre.
Bake at 120ºC for two hours. Then turn off the heat and let the Pavlova cool completely inside the oven.
In a frying pan put some chopped strawberries, raspberries, and a few blueberries with two tablespoons of sugar. Cook them for a few minutes until they release all their juice and let it cool.
Whip the cream with icing sugar. Fill the centre of the meringue with the whipped cream and pour the berry compote on top.
Finally, scatter over with some mixed berries and serve.