Combine flour, sugar, cocoa, baking soda and salt in large bowl. Add water, oil, vinegar and vanilla; stir with spoon or wire whisk just until batter is smooth and ingredients are well blended.
Pour into greased and floured 23 cm layer pan or 20 cm square pan. Bake at 180ºC or 35-40 minutes or until tester comes out clean. Cool in pan; frost as desired (I made a buttercream frosting recipe off a confectioner's sugar box which tasted really good with the cake.) Happy eating!!