Preheat oven to 375°F (190°C).
Mix together wheat bran and buttermilk; let stand. Combine oil, egg, brown sugar and vanilla and add to buttermilk – bran mixture.
Sift together flour, baking soda, baking powder and salt. Add to first mixture and stir until just blended.
Fold in diced strawberries and spoon into prepared muffin cups. To make topping, combine sugar, walnuts and cinnamon together. Cut in butter until mix resembles coarse crumbs. Sprinkle over muffins. Bake for 20 – 25 minutes.
* To substitute 2/3 cup (150 mL) buttermilk, use 2 tsp. (10 mL) lemon juice plus enough milk to make 2/3 cup (150 mL) total.