Preheat the oven to 325 degrees F and grease a 9x5-inch loaf pan and set aside.
In a medium bowl, whisk together flour, baking soda, and salt.
In a separate large bowl, beat together the egg, sugar, and vegetable oil.
Add the dry ingredients to the egg mixture and mix just until combined
Then add the milk, lemon, juice, vanilla extract, and bananas until fully incorporated.
Fold in blueberries and transfer the batter to the prepared pan.
Top with coarse sugar, if desired.
Bake for 60 to 65 minutes, until a toothpick inserted into the center comes out clean.
Cool on a wire rack and remove from the pan.