Sift flour, sugar, salt, soda, and cocoa together into a 9x13 inch ungreased cake pan. Make three wells. Pour oil into one well, vinegar into second, and vanilla into third well. Pour cold water over all, and stir with fork.
Bake at 350*F. for 30 to 40 minutes, or until toothpick inserted comes out clean. Frost with your favorite icing.
For Poke Variation (optional)
Poke cake every 1/2 inch with handle of wooden spoon. In medium bowl, beat pudding mix and milk with whisk about 2 minutes. Pour pudding evenly over cake. Run knife around sides of pan to loosen cake. Refrigerate about 2 hours or until chilled. Store loosely covered in refrigerator.
For Buttermilk Frosting:
Beat butter at medium speed with an electric mixer 1 minute. Gradually add powdered sugar alternately with 5 tbs buttermilk. Beat at low speed until blended. Stir in lemon juice, vanilla and salt. If desired, add up to 3 tbs buttermilk, 1 tbs at a time, beat to desired consistency.