Preheat the oven to 200 degrees C. Grease a 12 cup muffin tin or line with paper muffin liners. In a small bowl, mix together the wheat bran and buttermilk. Set aside to soak until thickened, about 10 minutes.
In a large bowl, use an electric mixer to blend together the brown sugar, vegetable oil, egg and molasses. Stir in the bran mixture. Combine the flour, baking powder, bicarb soda and salt; stir into the batter until just moistened. Mix in sultanas. Spoon batter into muffin cups, filling 3/4 full.
Bake for 15 to 20 minutes in the preheated oven until the tops spring back when lightly pressed.