Preheat the oven to 350º. Set aside a 10-by-3 1/2 inch tube pan ungreased.
Using an electric mixer, beat the egg yolks until thick and pale, about 3 minutes. Add the juice and zest and vanilla, then the potato starch, almonds, and salt; beat for 5 minutes, until very thick.
In a clean bowl, beat the egg whites until they hold soft peaks. Stir in one-fourth into the batter, then fold in the remaining whites until there are no white streaks.
Pour into the prepared pan and smooth the top.
Bake 40 to 45 minutes, until browned and a cake tester inserted into the center comes out clean. Immediately invert and let cool in the pan. When completely cool, run a knife around the edge to loosen and turn out of the tube pan onto a cake plate.
Serves 8 to 10.
The top can be glazed with chocolate, apricot preserves thinned with Grand Marnier or seedless raspberry preserves thinned with raspberry wine.