Preheat the oven to 350 degrees F.
Grease a loaf pan or line with parchment paper and set aside.
Make flax eggs and set aside to thicken.
In a bowl, mix all dry ingredients (flour, baking powder, baking soda, salt).
Make the buttermilk by mixing the oat milk with one tablespoon of lemon juice and set aside.
Mash the banana and set aside.
Mix together the flax eggs, buttermilk, mashed banana, vanilla extract, coconut sugar, lemon zest and the two remaining tablespoons of lemon juice.
Add the wet mixture to the dry mixture and gently mix until combined.
Fold in the blueberries.
Bake for 50 minutes or until a toothpick inserted in the center comes out clean.
Let cool for at least ten minutes.
Slice and enjoy your vegan sweet lemon blueberry loaf!