Combine the flour, baking soda, baking powder, and 3/4 teaspoons salt in bowl and set aside. Beat the egg whites with 1/8 teaspoon salt in a bowl or mixer until soft peaks form. Set aside. Cream the butter and sugar in a large bowl until light and fluffy. Add the egg yolks to the butter mixture one at a time, beating well. Add the lemon zest. Combine the lemon juice and milk in a small bowl. Add the flour mixture to the creamed butter, alternating with the lemon juice mixture. Fold in the egg whites. Spread the batter evenly in a greased 9 inch springform pan. Bake at 350 degrees for about 50 minutes or until top is golden and cake springs back when touched in center. Remove from oven and run a knife around the edges of the springform pan if cake is sticking to pan.
For Syrup:
Combine all syrup ingredients until sugar dissolves, spoon over cake while still warm. Let cool and remove from pan. The syrup will crystallize as the cake cools.
For icing:
Place the sour cream in a mixing bowl with 2 cups of the powdered sugar. Mix and add salt and lemon juice. Add more powdered sugar until icing is desired consistency. Frost cake when completely cooled.
Notes
-This recipe would work in 2 large loaf pans, or one 9x 13 pan.-I made a few modifications, because I really like a strong lemon flavor. The original recipe only calls for 1 tablespoon of zest, and no lemon icing. I think I may cut about 1/4 cup of the sugar in the cake next time as well