Preheat oven to 350. Mix together flour, salt, baking soda, cocoa, and sugar. Add the oil, coffee, milk, eggs and vanilla.
Pour into lightly greased 9x13 baking pan and bake 40 minutes or until cake is baked. Let cool before icing it.
Frosting-Cream butter in mixer, then add the cocoa and blend. Add egg and mix well. Add lemon juice and beat until smooth. Add powdered sugar slowly until frosting is smooth and creamy. Frost your cake and serve.