Grease tube pan; preheat oven to 160ºC . Set two sticks of butter aside to soften. Separate eggs; beat whites till stiff and set aside. Cut butter into sugar. Add egg yolks and beat a little. Measure flour; use a small amount to mix with nuts until they are well-floured. Mix soda into flour. Stir flour into butter/sugar/egg mixture. Add sour cream and vanilla. Can do all this with an electric mixer, but now use a spoon to fold in egg whites. Fold in nuts and bake approximately 1.5 hours until done.