You can substitute apple sauce for oil. The substitution ratio is 1:1.
You can substitute flax seeds for eggs. 1 T. ground flax seeds + 3 T. water = 1 egg
You can substitute maple syrup for sugar. The substitution ratio is 1:1.
You can substitute masa harina for white flour. The substitution ratio is 1:1.
You can substitute baking soda and cream of tartar for baking powder. 1/4 t. baking soda + 1/2 t. cream of tartar = 1 t. baking powder