Heat oven to 350*F. Spray a 9 X 13 baking pan with vegetable spray
In a medium-size bowl combine the water, vinegar, oil, sugar, pumpkin, and vanilla. Stir to combine. Set aside.
In a separate bowl stir together the flour, cornstarch, salt, baking soda, and spices. Whisk until well combined. Create a well in the middle of the flour ingredients.
Pour the pumpkin mixture into the bowl with the flour mixture. Use a whisk to stir until well-combined.
Pour the batter into prepared cake pan and bake for about 35 - 40 minutes. Insert a tester in the center. If it comes out clean or mostly clean (with only a few crumbs), the cake is done. If not, return it to the oven and bake for another 5 minutes or so.
When the cake is done, remove it from the oven and allow it to cool completely before adding the Vegan Cream Cheese Frosting.