1Preheat oven to 350 degrees Fahrenheit.
In an 8×8-inch ungreased baking pan, mix together the flour, cocoa, sugar, baking soda, and salt. Shake pan to flatten out the mix.
Make one large indentation and two small indentations in the dry ingredients.
Pour vinegar in one small indentation, vanilla in the second small indentation, and the vegetable oil in the large indentation. Pour water over all and with a fork, stir until batter is smooth.
Bake in the middle rack of the oven for 35 minutes or until the a toothpick inserted in the center of the cake comes out clean.
Cool on a baking rack and sprinkle with powdered sugar or top with your favorite frosting.
Double the ingredients to make a 9 x 13-inch cake