Sift flour, sugar, salt, soda and cocoa together into a 9x13" ungreased cake pan. Make 3 wells. Pour oil into one well, vinegar into second, and vanilla into third well. Pour cold water over all, and stir well with fork until completely mixed.
Bake at 350° F for 30 to 40 minutes, or until tooth pick inserted comes out clean.
Frost with your favorite icing, or the below
Frosting: Whip frosting ingredients together until smooth
Notes
You can vary the frosting by adding melted chocolate, instant coffee for a mocha flavor or sometimes I melt brown sugar in the butter before adding to the powdered sugar. Walnuts are good either mixed in cake or sprinkled on top.