Preheat oven to 475 degrees F.
In a large bowl, whisk together flours, bran, cream of tartar, baking soda, cinnamon and nutmeg. Stir in sweet potatoes and raisins.
Add buttermilk and oil. Turn out onto a floured breadboard. With floured hands, knead mixture for mins.
On the same board, toll dough 1/4-inch thick. Cut out 1 1/2-inch rounds. Transfer to a lightly oiled baking sheet. Use all dough by rerolling leftovers.
Bake f or 6-8 mins. Serve warm.