Prepare a bundt pan by lightly spraying the interior with cooking spray. Next, lightly sprinkle flour around the interior of the pan - it should easily stick to the cooking spray. Do not over flour the baking surface!
Using a large mixing bowl, whisk together the sifted flour, sugar, cocoa powder, baking soda, and salt until well blended.
Add the mayonnaise to the flour mixture, along with the water and vanilla extract.
Use a sturdy wooden spoon to stir the ingredients together until well incorporated.
Spoon the batter into the bundt pan. Bake for 30-35 minutes. Check for doneness by inserting a wooden toothpick into the cake. If the toothpick comes out clean, the cake is ready; if not, allow to bake for 2 minutes longer.