Prepare a baking pan by lining it with baking paper. Draw a 20 or 22cm diameter circle on the baking paper to use as a guideline later on.
Mix the egg whites with the lemon juice and salt in a bowl until fluffy.
Add the sugar, gradually, mixing all the time. Once you added all the sugar, continue mixing until the meringue is stiff and glossy and you don't feel the sugar granules anymore.
Using a spatula, fold in the vanilla, vinegar and cornstarch.
Spread the whipped mixture over the baking paper, trying to keep the meringue into the circle you draw earlier.
Bake for 1 1/2 hours in the preheated oven then turn the oven off and leave the Pavlova inside for 30 more minutes.
Vanilla diplomat cream:
Bloom the gelatin in cold water.
Heat the milk with the vanilla bean in a saucepan.
Mix the egg yolks with sugar in a bowl. Add the cornstarch and mix well then pour in the warm milk.
Return back on heat and cook for 1 minute from the moment it starts to boil, mixing all the time to prevent sticking to the bottom of the pan or burning.
Remove from heat and stir in the gelatin.
Cover with plastic wrap and allow to cool down completely.
Once chilled,remove the vanilla bean then mix the cream until smooth once again. Fold in the whipped cream.
Spread the vanilla diplomat over the Pavlova then top with fresh berries.