bran muffin recipebran muffin recipe

1 1/2 cups wheat bran - 1 cup buttermilk - 1/3 cup vegetable oil - 1 large egg - 2/3 cup brown sugar, packed - 1 teaspoon vanilla extract - 1 cup all-purpose flour - 1 teaspoon baking soda - 1 teaspoon baking powder - 1/2 teaspoon salt - 1/2 cup raisins or dried cranberries (optional)