Preheat the oven to 350º F (180° C). Place parchment paper on a rectangular baking sheet.
In a clean and dry bowl whisk the egg whites with a mixer until soft peaks form (about 5 minutes). Whisk in the sugar in two additions and beat for 2 minutes after each addition. Now the peaks forming will be stiffer and won´t move as much when you lift up the mixer whisk.
Add in the vanilla, the cornstarch, vinegar and salt and beat for 1 more minutes. Using a spoon, form circles using the mixture, forming the pavlovas, and with the backside of the spoon make a hole in the middle of each, to leave some space for the whipping cream and strawberries.
Put thebaking sheet in the oven and as soon as you close the oven door bring the temperature down to 190º F (90°C). Bake until the pavlovas are firm and dry, for about 90 minutes. It is important not to open the oven door while baking them so no air comes in.
Once the time has passed, turn off the oven but leave the pavlovas in it to cool down while still there. Once cold you can serve immediately or keep in a cool dry place for 2 days.
To decorate:
To make the sauce put a sakillet on the stove to medium heat. Wash and cut half of the strawberries in small cubes and add put them on the skillet with the sugar. Cook for 8 minutes aprox. until a thick sauce forms.
Once this time has passed, add in the lemon juice and cook for 2 more minutes. Remove from the heat and once cool decorate the pavlovas with the whipping cream, the strawberry sauce and whole strawberries.