Prep the pan
Position a rack in the center of the oven and preheat to 180° C. Line a deep round cake pan with parchment paper, letting the paper come up the sides so the cake lifts out cleanly.
Whisk the eggs
In a large bowl, beat the Eggs with the Granulated Sugar, the finely grated zest of the Lemon if you're using it, and the Salt until the mixture is very pale, thick, and falls from the whisk in a ribbon, about 8-10 minutes.
Fold in flour
Sift the All-purpose Flour over the whipped eggs in 2 or 3 additions, and fold gently with a spatula just until no dry streaks remain. Work from the bottom of the bowl and turn the batter over rather than stirring in circles, so you keep the foam light.
Bake the cake
Scrape the batter into the prepared pan and smooth the top without pressing it down. Bake for 25 minutes at 180° C, until the cake is golden, set at the edges, and just springs back in the center; a skewer near the edge should come out clean.
Cool the cake
Set the pan on a rack and let the cake rest for 10 minutes. Use the parchment to lift it out, then let it cool on the rack for 20 minutes more, or until just barely warm and fully set.
Slice and serve
Peel away the parchment, cut the Pão de Ló into wedges, and serve it plain while the crumb stays soft and airy.


vegetarian






