Preheat oven to 375°F and line a muffin tin with liners.
In a small bowl, mix the oat milk and apple cider vinegar. Set aside for a few minutes to create a vegan “buttermilk.”
In a large bowl, whisk together the flour, baking powder, baking soda, salt, sugar, and lemon zest.
Add the oat milk mixture, vegetable oil, and vanilla extract to the dry ingredients. Stir until just combined.
Gently fold in the blueberries, being careful not to overmix.
Divide the batter evenly between muffin cups.
Bake for 20–25 minutes, or until a toothpick inserted in the center comes out clean.
Let cool slightly, then enjoy.