Preheat oven to 350 degrees F. Line a baking sheet with parchment paper and set aside.

In a medium bowl, or the bowl of your electric stand mixer, beat the egg whites on medium speed until soft peaks form. Slowly stream in the sugar and beat until the whites are stiff and glossy, about 4 minutes. Stir in the lemon juice, 1 teaspoon vanilla, cornstarch and salt. Fold in about 1/4 cup of the chopped pistachios until evenly combined.

Spoon the meringue onto the prepared baking sheet into 6 or 8 (depending on how big you want them) mounds. Using a spoon or small offset spatula, shape them into circles, with a big well in the center. Sprinkle with 2 tablespoons of the remaining chopped pistachios and bake for 5 minutes. Lower the oven temperature to 250 degrees F and bake for 1 hour. Then turn off the oven and prop open the door with a wooden spoon handle and leave the meringues in there for 1 hour until completely cooled.

Beat the heavy cream on high until soft peaks form. Add the powdered sugar, and remaining 1/2 teaspoon vanilla extract. Continue to beat until stiff peaks form, but be careful not to overdo it because it'll end up like butter.

To assemble the pavlovas, spoon a bit of the whipped cream into the center of each and top with a spoonful of the blood orange curd, a slice of blood orange, and a sprinkling of the remaining chopped pistachios. Serve immediately. The meringues can be made the day before and stored in an airtight container at room temperature.