Preheat the oven to 180 degrees C. Line a 12 cup deep muffin pan or cupcake tin with paper muffin cases.
Mix together 2 teaspoons oat bran, 1 teaspoon cinnamon and the raw sugar, and set aside for the topping. Place the remaining oat bran in a bowl with the soy milk and leave to soak for 5 minutes.
Peel and roughly mash the bananas. Add the brown sugar, oil, vanilla essence and egg white, and beat well together.
Sift the plain and soy flours, baking powder and remaining cinnamon into a large bowl. Make a well in the centre and stir in the soaked oat bran and the banana mixture. Mix lightly but thoroughly, just until smooth.
Spoon the mixture into the paper cases and sprinkle with the topping. Bake for 20–25 minutes or until well risen and golden-brown. Lift the muffins out onto a wire rack to cool a little. Serve fresh, preferably still slightly warm from the oven. These muffins are best eaten on the day they are made.