Preheat oven to 350ºF.

With an electric mixer or stand mixer, whisk egg whites with salt until the whisk leaves "trails" in the mixture.

Slowly add in sugar, one tablespoon at a time, while beating for at least 10-15 seconds after each addition until all the sugar is dissolved.

Stop beating when the meringue reaches stiff peaks. Rub a bit of meringue in between your thumb and index finger - it should feel smooth without being gritty.

Sprinkle cornstarch, vanilla, and vinegar onto meringue and fold with a rubber spatula until combined.

Transfer meringue into a piping bag fitted with a closed star tip.

On a baking sheet lined with parchment paper, pipe a filled-in circle for the base of the pavlova. Pipe a ring on top of the outer edge of the circle to create the "walls" of the pavlova and an empty space in the middle for the filling.

Put the baking sheet in the oven and immediately turn oven down to 300ºF. Bake pavlovas for 30 minutes.

Turn off the oven and leave them in the oven for another 30 minutes until they peel cleanly off the parchment paper.

Set aside to cool completely. Fill with blood orange curd just before serving.

In a small pot, add egg yolks, sugar, blood orange zest, and blood orange juice.

Cook on medium-high heat while stirring constantly until it thickens enough to coat the back of a spoon or is a jelly-like consistency, about 3-4 minutes. Stir vigorously to prevent getting scrambled eggs!

Remove from heat. 

Stir in butter, one cube at a time, dissolving the previous cube of butter before adding the next until all the butter is incorporated. You should be able to "cut" through the curd with a spatula and the two sides of curd take about 1-2 seconds to come back together.

Transfer curd to a small bowl and press plastic wrap directly onto the surface of the curd to prevent a skin from forming.

Let cool completely before spooning into pavlovas. Top with slices of fresh blood orange and a sprinkle of blood orange zest.