Preheat the oven to 350°F Grease and parchment paper line a 10 inch tube pan, set aside.
Beat the eggs with the salt until light. Gradually beat in the sugar at medium speed and beat for at least 20 minutes, add rind if using.
In a separate bowl combine the flour and baking powder and stir with a fork or whisk. At low speed, add the flour mixture to the eggs one heaping tablespoon at a time, blending well after each addition, and scraping down the sides of the bowl when necessary.
Pour the batter into the pan and bake for approximately 35 minutes, or until a cake tester inserted comes out clean (cake will spring back to a light touch). If you like a crust on the top of the cake, sprinkle the 1 tablespoon of sugar on top of the batter prior to baking.
Let the cake cool in the pan for 10 minutes, then remove from pan and peel off parchment paper. Let cool completely on rack. Dust with icing sugar before serving if desired.