Preheat oven to 375ºF. Prepare a 12-cup muffin tin by lining with papers or greasing well.
Pour boiling water over wheat bran in a large bowl and stir until absorbed. Stir in brown sugar, vegetable oil and egg.
In a separate bowl, whisk together flour, baking powder and salt. Add to bran mixture, gently stirring until mostly combined (there should still be a few floury streaks). Fold in blueberries, then divide batter among muffin cups. Bake 15-20 minutes, until tops feel springy when gently pressed. Transfer to wire racks to cool.
Video
Notes
Checking Doneness: You can use a toothpick to check doneness, but I prefer to take the internal temperature: they'll be done and perfectly moist at 190ºF.Frozen Blueberries: I like to use frozen wild blueberries because they're small and flavorful.If your frozen blueberries are large, toss them in a little flour (about 1 tsp) before folding them into the batter. This helps absorb excess moisture and prevents the berries from sinking or releasing too much juice as they bake. You can also slightly reduce the amount of blueberries to avoid the muffins becoming overly wet or leaving pockets of under-baked muffin batter.