Add all ingredients to quart-sized zip-top bag. Squeeze out as much air as possible and seal.
Label with baking instructions and date, and store in a cool dry place until ready to use.
Add dry ingredients to large bowl. Add 2 ½ cups water. Stir just until combined. Batter will be slightly lumpy.
Grease and flour a 9x13 pan or dish, and dust with a little cornmeal. Pour batter into prepared pan/dish.
Bake at 350 Fahrenheit for 23-30 minutes, or until toothpick or knife stuck into center comes out clean.
