Preheat the oven to 400°F. In a small bowl, whisk the flaxseed with water and set aside for 5 minutes. In a medium bowl, mix sweet potato, applesauce, olive oil, lemon juice, sage, and the flaxseed slurry. In another medium bowl, mix the flour, baking soda, and salt. Add the wet ingredients to the dry ingredients and stir well to combine. Line a baking sheet with parchment paper and grease it with ghee or olive oil