Heat the oven to 250F.
In an electric mixer fitted with the whisk attachment, beat the egg whites and salt on high speed until stiff peaks form, about 4-5 minutes. Reduce speed to medium, and add the sugar slowly over the course of 2 minutes.
Scrape down the sides and bottom of the bowl with a spatula. On high speed, whip for 6-7 minutes more until glossy, stiff peaks are formed. (You should be able to turn the bowl completely upside down and the meringue will not budge!)
Add the vanilla, vinegar, and cornstarch and mix until just combined.
Line a large baking sheet with parchment. Spread or pipe the meringue onto the parchment in any form you choose.
Bake the pavlova for 45 minutes without opening the oven door. After 45 minutes, turn off the oven and leave the pavlova inside with the door closed for 3 hours. Then, open the oven door and let the pavlova sit for 30 minutes more. (All of this will keep your pavlova from cracking!)
Right before serving, top the pavlova with the whipped cream, blood orange curd, and blood orange slices. Serve right away. (If left to sit, the pavlova will become soggy.)