Pre-heat oven to 350 degrees.
In a large cast iron skillet, combine onions, celery, carrots, sage, salt and pepper with a two tablespoons of fat. Saute over medium-low heat until veggies are softened (approximately ten minutes). When done, remove vegetables from pan.
Meanwhile, in a large bowl, combine the flour mix, cashew meal, baking soda and salt; stir thoroughly. Add melted oil, eggs, and broth, stirring after each addition (the batter will be somewhat stiff until Fold in sauteed vegetables.
(There should still be some oil remaining in the skillet from cooking the vegetables; if not, add another tablespoon. Pour the batter into the skillet; bake for 40 minutes or until top is browned and crusty. Remove from oven and allow to cool before serving.