Preheat the oven to 325°. Lightly grease a 12-muffin pan. In a mixing bowl, whisk together flour, salt, baking soda, cinnamon, and nutmeg.
In a separate bowl mix together the sugar, oil, eggs, and vanilla. Stir into the dry ingredients. Add the mashed sweet potato, cranberries, and pecans, mixing well.
Fill muffin cups ⅔ full. Bake 22-25 minutes. Extra muffins keep best in a closed brown paper bag on the counter for a day or two. After that the muffins can be frozen in the brown bag for a couple of weeks.