Combine flour, sugar, baking soda and salt in a large bowl and mix well. Bring butter and water to a boil in a large saucepan. Remove from heat and pour over flour mixture. Stir in eggs, sour cream, lemon peel, vanilla extract and lemon extract.
Pour into a greased 15 x 10-inch pan. Bake for 25 to 30 minutes or until cake is golden brown.
For icing, combine butter and milk in a saucepan; bring to a boil. Remove from heat and add powdered sugar and lemon extract. Beat until smooth. Pour over hot cake.