Preheat oven to 180°C.

Beat sugar, eggs, vanilla and melted butter in a large mixing bowl by hand.
You don't need an electric mixer for this batter
Tip: wait a bit for the butter to be cool before adding eggs

Add self rising flour and cocoa to bowl.
Mix well. And add oil. This is a very thick batter.

Pour into a greased or use parchment paper lined 8 inch square baking dish.
Spread evenly.

Place in 180°C oven for 25 - 35 minutes or until tested with a toothpick that comes out with a few crumbs on it. I usually leave it for 35 min, You don't want to over bake the brownies.
Cool. Then cut into squares.