Preheat oven to 400 degrees. In a bowl combine cornmeal, Stevia Powder, salt, Cream of Tartar, and baking soda. Whisk until well combined. Set aside. Blend together egg , whites, almond milk, sourdough starter, and corn. Set aside. In a 10 inch cast iron skillet, sauté onion and pepper in butter until soft. When veggies are soft, remove from the skillet into another dish. Spray the hot skillet lightly with Olive Oil Pam Spray. With a whisk combine the dry ingredients with the wet ingredients just until combined. Pour into the hot prepared skillet. Sprinkle the sauted veggies over the cornbread. Add the jalapenos if desired. Place skillet into preheated oven. Bake for 20-30 minutes or until a toothpick inserted in the center comes out clean. Serves 8.