In a large bowl, whisk together the flour, sugar, baking soda, and salt. Set aside.
In a medium-sized bowl, mash the bananas with a fork. Stir in the pureed avocado, yogurt and pure maple syrup. Add the eggs, one at a time, and stir to combine. Add in the vanilla and stir to incorporate.
Add half of the dry ingredients into the wet and stir until combined. Repeat with remaining dry ingredients.
In the same bowl as the flour mixture, toss together the 1 Tbsp. flour and blueberries. Pour into the batter, and fold the blueberries in. Pour into the prepared loaf pan.
Bake for 60 minutes until a toothpick inserted in the center comes out clean.
Move the loaf pan to a wire rack and let cool for 5-10 minutes before slicing.