In a large bowl, whisk together the cake mix, flour, sugar and salt. Add the remaining ingredients and beat with hand mixer for 2 minutes, or until well blended.
1 (18.25 ounce) box of chocolate cake mix, 1 cup all-purpose flour, 1 cup granulated white sugar, 3/4 teaspoon salt, 1 1/3 cups water, 2 Tablespoons vegetable or canola oil, 1 teaspoon vanilla extract, 1 cup sour cream, 4 large eggs