Add 1 cup of the cooked, mashed sweet potato to a blender. Add in maple syrup, coconut oil, 2 tablespoons water, lemon juice, apple cider vinegar, vanilla, and sea salt. Blend until smooth and creamy. If not blending well, add 1-2 tablespoons water at a time to achieve a smooth consistency. Be careful not to add too much water as it will make the frosting too runny.