For the pavlova, whisk the egg whites and vanilla to stiff peaks, then gradually whisk in the sugar, 1 tbsp at a time. Finally, fold in the corn flour and vinegar. Pipe or shape the pavlova into a rectangle on a tray lined with non-stick baking paper, making a dip in the middle. Bake in the oven at 150`c for approximately 1 hour. Meanwhile, make a berry compote by cooking together the frozen strawberries, 2 tbsp sugar and lemon zest together in a pan for 15-20 minutes. Allow to cool down completely. To make the filling, whip the cream to soft peaks with the icing sugar and vanilla, then whisk in the mascarpone. To put the pavlova together, place the meringue onto a serving tray and fill with the strawberry compote. Top with the whipped ricotta mixture and top with fresh whole and sliced strawberries, mint leaves and white chocolate shavings.