Preheat oven to 375°F.
Sift or stir together flour, cocoa, baking soda, salt and sugar in ungreased 8 inch square baking pan.
If you have a 4 cup liquid measurer, then measure and stir in oil, water, and vanilla directly in the measuring cup or if not, then in a medium bowl, stir in the liquid ingredients. Then pour into the baking pan mixing into the flour mixture with a fork or wire whisk until smooth.
Stir in apple cider vinegar just until evenly distributed. As it reacts to the baking soda, it will cause pale swirls in batter initially, but that will disappear when baked.
Bake for 25-30 minutes, or until cake springs back when lightly pressed in centre. Cool thoroughly in pan on wire rack.
Sprinkle the brownie with icing sugar, and serve with fruit.
