Preheat oven to 375 degrees F (190 degrees C). Grease muffin cups or line with paper muffin liners.
Mix together wheat bran and buttermilk; let stand for 10 minutes.
Beat together oil, egg, sugar and vanilla and add to buttermilk/bran mixture. Sift together flour, baking soda, baking powder and salt. Stir flour mixture into buttermilk mixture, until just blended. Fold in raisins and spoon batter into prepared muffin tins.
Bake for 15 to 20 minutes, or until a toothpick inserted into the center of a muffin comes out clean. Cool