Preheat oven to 375°F (190°C). Line your muffin tin with paper liners or lightly grease it.

In a small bowl, combine the dairy-free milk and apple cider vinegar. Let it sit for 5 minutes to slightly curdle.

In a large bowl, whisk together the flour, sugar, salt, and baking powder.

Add the oil, milk mixture, and vanilla extract to the dry ingredients. Stir gently until just combined—do not overmix.

Fold in the blueberries using a spatula. If using frozen blueberries, toss them lightly in flour first to prevent sinking.

Divide the batter evenly among the 12 muffin cups. If desired, sprinkle tops with coarse sugar for extra crunch.

Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.

Allow muffins to cool in the tin for 5 minutes, then transfer to a cooling rack to cool completely.