Preheat the oven to 350F/176C convection (325F/163C conventional) and line two un-greased 8 inch baking pans with parchment paper or use a tube pan.
Make sure to clean your pan, metal bowl and whisk for the stand mixer well. I wipe it with a little vinegar after cleaning to make sure there is no greasy residue.
Place the egg whites in the bowl of the stand mixer with the lemon juice (or cream of tarter) and turn the mixer up to medium-high speed.
12 large egg whites, 1 Tbsp lemon juice
Beat for a minute or so and when the egg whites look frothy, stream the sugar into the bowl with the mixer going. It should take about a minute to get all the sugar in slowly.
1 3/4 cups (350g) granulated or superfine sugar
Continue beating for a few minutes, just until the meringue reaches a soft peak (see image in blog post). Add the vanilla and mix again just until it's combined.
2 tsp vanilla bean paste
Sift in the cake flour and salt, turn the mixer up to medium-low speed, just until the flour is mostly combined, about 30-60 seconds. Use a rubber spatula to scrape the edge of the bowl and fold the batter a couple more times until it's well combined.
1 1/4 cup (144g) cake flour, 1/4 tsp fine sea salt
Spread the cake into two UN-GREASED 8 inch cake pans. Make sure to spread the batter evenly with an offset spatula or spoon because the lack of fat will prevent it from spreading and if left uneven, it will bake uneven.
Bake for about 25 minutes. Press gently on the top center and there should be a slight bounce/resistance and no wet batter.
Remove from the oven and flip over onto a cooling rack (not a flat surface or it will sweat) and allow it to cool completely to room temperature, 1-2 hours.