Preheat the oven to 400°F (200°C). Line a 12-cup muffin tin with paper liners or grease the cups.
In a large bowl, whisk together the flour, granulated sugar, salt, and baking powder.
In a separate medium bowl, combine the vegetable oil, egg, milk, and vanilla extract. Beat until well blended.
Pour the wet ingredients into the dry ingredients and stir gently until just combined. Do not overmix; the batter should be lumpy.
Fold in the fresh blueberries carefully to avoid breaking them.
Divide the batter evenly among the muffin cups, filling each about 2/3 full.
Sprinkle the tops of the muffins with coarse sugar for a crunchy topping.
Bake in the preheated oven for 18 to 20 minutes, or until a toothpick inserted into the center comes out clean.
Remove the muffins from the oven and allow them to cool in the pan for 5 minutes.
Transfer the muffins to a wire rack to cool completely before serving.