Sift flour and cocoa into a bowl. Stir in the sugar. Add water, oil, vinegar and vanilla. Mix all ingredients well, until a smooth mixture forms.

Line regular-sized cake tin with greaseproof paper, then grease with canola spray. Pour mixture into tin. Bake in oven for 35 minutes. Test cake with skewer to ensure it is baked through. Dust with icing sugar or ice with vegan icing.