How to cook
Sift the flour into a bowl. Add the remaining dry ingredients for the cake - cocoa, ground walnuts, soda and sugar. Stir well.
Add the liquid ingredients - vinegar, water and oil. Stir, until a homogeneous mixture is obtained.
Grease and flour a baking pan and pour the mixture in it.
Preheat the oven to 360°F (180°C). Bake the brownie for about 30 minutes or until it is fully baked.
The lean brownie with walnuts is very tasty.