Preheat oven to 275 degrees F. If desired, trace 6-8 circles onto a piece of parchment paper with a pencil (the top of a large, wide-mouth mason jar or drinking glass works well). Flip paper over and lay on baking sheet. Set aside.

Place sugar and corn starch in a small bowl and whisk together. Place egg whites in a stand mixer with whisk attachment. Beat for 1-3 minutes, until soft peaks form. With mixer running on medium-high speed, slowly add sugar mixture, one spoonful at a time until all is incorporated. Increase speed to high and continue mixing 3-4 minutes longer, until mixture is smooth and glossy and holds stiff peaks.

Add vanilla and vinegar and mix to combine, scraping down edges with spatula. Place mixture in a piping bag and pipe rounds onto prepared sheet. (Alternately you may simply spoon mixture onto the 8 rounds and shape with a spoon.)

Use a spoon to make a little indentation in the center of each mound.

Place pan in oven and decrease temperature to 250 degrees. Bake for 45-50 minutes, until edges are set and sound hollow when tapped. Turn off oven and with oven door cracked open, let pan cool completely.

Pavlova shells may then be stored in air-tight containers for a day or two, or filled.

To fill, whip cream, vanilla, and sugar until soft peaks form. Spoon into center of each shell and then top with desired fruit.