Gluten-Free Banana Bread

1 teaspoon margarine, or as needed, softened
3/4 cup almond milk
1 tablespoon vinegar
1 1/4 cups rice flour
1/2 cup brown sugar
1/4 cup amaranth flour – We use http://amzn.to/2yV1t0H
1/4 cup soy flour
1/4 cup flax seed meal – We use http://amzn.to/2A82irg
1 teaspoon baking powder – We use http://amzn.to/2zMy1NM
1 teaspoon baking soda – We use http://amzn.to/2hEzfUy
1 teaspoon sea salt – We use http://amzn.to/2yTpxBg
2 large bananas, mashed
1 egg, beaten
1 tablespoon coconut oil, melted

1. Preheat oven to 350 degrees F (175 degrees C). Lightly grease an 8-inch square metal baking dish with margarine.
2. Mix almond milk and vinegar together in a cup.
3. Mix rice flour, brown sugar, amaranth flour, soy flour, flax seed meal, baking powder, baking soda, and sea salt together in a large mixing bowl.
4. Beat bananas, almond milk mixture, egg, and coconut oil together in a separate bowl; add to rice flour mixture and stir until dry ingredients are completely moistened. Spread the mixture into the prepared baking dish.
5. Bake in the preheated oven until a toothpick inserted into the center comes out clean, about 35 minutes.