Preheat oven to 225 F. Line a sheet pan with parchment paper. If you are planning to make a domed pavlova, trace a 7 inch circle on the parchment paper and flip it over. If you are making it sheet pan style, draw a rectangle the size of half the sheet pan.
Place egg whites in a heat proof bowl along with the sugars, whisk immediately (if you don’t whisk, the sugar ‘cooks’ the eggs).
Bring a pot filled a bit less than halfway with water to a simmer and place the bowl over it. Whisk it over the water until it’s light and frothy and there are no sugar granules when you press the mix between two fingers.
Whip the mix on medium for about 4 minutes, until you reach medium to stiff peaks. Right before you are done whipping, add the salt, vanilla, spices, cornstarch and vinegar. Dollop the meringue onto the prepared parchment pan.
Using an offset spatula shape the meringue: for a dome smooth out the sides and make a slight well in the center. For a sheet pan style, smooth it out flat, it should be about an inch high.
Bake the pavlova for 1 1/2 hours if it's sheet pan, 2 hours if it's domed. Check doneness by touch - if the pavlova is dry to the touch it's done. Avoid opening the oven as much as possible. At the 2 hour mark, shut off the oven and leave them in for another two hours, or overnight.