Preheat oven at 180 deg C ( 360 deg F), Grease & Flour a 9 x 13inch baking dish. Place the sifted flour,cocoa, sugar, soda & salt together & sift into a large bowl, mix well together.
Add Oil, Water Vanilla essence to the sifted ingredients and blend well together at least for 5 mins .
Now pour the smooth mixture into a 9 x 13 inch greased and floured baking dish. Allow to bake for about 1 hour.
Check if it's done by inserting a toothpick/Knife in the center, if it comes out clean then the cake is done.