Preheat your waffle iron according to the manufacturer’s instructions.
In a small bowl, whisk together the oat milk and the apple cider vinegar. Set aside.
In a medium sized mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder and salt.Add the oat milk mixture, melted vegan butter and vanilla extract to the dry mixture. Stir until just combined. Fold in the blueberries.
Lightly grease the waffle iron with oil or non-stick spray. Pour the batter into the preheated iron (amount depends on your waffle maker). Close the lid and cook until golden brown and crisp, usually 4–6 minutes.
Serve the waffles hot with maple syrup, extra blueberries, or a dollop of vegan yogurt or whipped cream.