Sift flour, sugar, cocoa, baking soda and salt directly into an ungreased 11x13-inch pan. Using a fork or whisk, stir the dry ingredients in the pan together well. Make three holes in the center.

In one, pour oil; in the second, add the vanilla, and in the third hole, put the vinegar. Pour cold water over all. With the fork, mix well, being sure to draw out mixture from the corners to mix into the batter.

Bake at 375°F for about 35 minutes, or until a toothpick inserted in center of cake comes out nearly clean.