Preheat the oven to 350 degrees. Butter and flour a 9 inch loaf pan. Set aside.
In a large mixing bowl, whisk together the oil and honey until combined. Add the eggs. Whisk until fully combined.
Stir in the vanilla and the mashed bananas.
Stir in the flour and salt.
In a small, separate bowl, add the baking soda to the hot water. Let it fizz. Add the fizzy mixture to the rest of the batter.
Blend in the chopped walnuts.
Lightly toss the blueberries in whole wheat flour. Carefully stir in the blueberries into the batter until just combined. Pour batter into greased pan.
Bake for 50-60 minutes. Let cool on a wire rack for 10 minutes before removing from pan.
Store in airtight container for up to a week (if it lasts that long!).