Put all of the ingredients into a mixing bowl or the bowl of a stand mixer. Use a large spoon or rubber spatula to slightly combine the ingredients. (This will prevent the batter from flying out of the bowl when you turn the mixer on.) Then use an electric mixer or stand mixer and beat at medium speed for 2 minutes.
1 box red velvet cake mix, 1 cup all-purpose flour, 1 cup granulated sugar, 3.4 ounce instant chocolate pudding mix, 1 tbsp cocoa powder, 1 tsp vanilla extract, ¾ tsp salt, ½ cup vegetable oil, 1 cup sour cream, 1⅓ cups water, 4 eggs