Oven Temp ~ 350° Baking Time ~ 1 1/4 to 1 1/2 hours
Position a rack in the center of the oven, and preheat. Lightly butter a pan and dust with flour tapping out the excess.
Sift together the flour, 1/4 teaspoon of the salt, and the baking soda. In a large bowl, using a hand-held electric mixer set at high speed, beat the butter until creamy, about 1 minute. Add the sugar and beat until light in color and texture, about 2 minutes. Beat in the egg yolks, one at a time, beating well after each addition. Then add the vanilla. Reduce the speed to low, and in thirds, alternately beat in the flour mixture and sour cream.
In a large greaseproof bowl (I use glass), using a hand-held electric mixer (clean beaters) set at low speed and beat the egg whites until foamy. Add the remaining 1/4 teaspoon salt, increase the speed to high, and beat until the whites just form stiff peaks. Stir about one fourth of the beaten whites into the batter; then fold in the remaining whites. Transfer the batter to the prepared cake pan, smoothing the top.
Bake until the cake is golden brown and a toothpick or bamboo skewer inserted comes out clean.
Cool the cake completely on a wire rack. Run a long knife around the edges to release the cake from the pan, then turn out onto a serving plate.
Variations on flavoring: In addition to the Vanilla, add either grated zest of lemon or orange or 1/2 teaspoon of rum or brandy extract.
Imagine it smothered with strawberries and whipped cream..... okay its great even by itself.