Beat the egg whites on the highest speed until just stiff. Add the sugar 1 tablespoon at a time, mixing well to incorporate each addition before adding the next.
In a small bowl combine corn starch, vanilla extract and lemon juice until smooth. Fold into egg white mixture.
Spread half the batter onto a parchment lined cookie sheet in the shape of a triangle, about 10"-11" per side. Place the remaining batter into a pastry bag fitted with a star tip and pipe 2 rows of stars around the perimeter of the triangle. (You can skip this step for a more rustic pavlova and spread all the batter, smoothing with the back of a spoon. Make sure the center of the triangle is lower than the sides as it will need to hold a filling.)
Bake 55 minutes.
Turn off the oven and allow to cool in the oven with the door slightly ajar.
Prepare the topping. Whip the topping, set aside. Toss the berries with the sugar, set aside.
To assemble, spread the whipped topping in the well in the center of the triangle as far out to the sides as you'd like making sure to maintain triangular shape. Top with mixed berries, again making sure to maintain triangular shape. Enjoy immediately.
Recipe by Cooking With Tantrums at https://cookingwithtantrums.com/2018/02/hamentash-pavlova/