Preheat oven to 400°F (200°C). Line a muffin tin with paper liners.
In a large bowl, combine flour, sugar, salt, and baking powder.
In another bowl, mix vegetable oil, egg, and milk.
Add wet ingredients to dry ingredients and stir until just combined.
Fold in blueberries, lemon zest, and lemon juice.
Fill muffin cups about ⅔ full.
Bake for 20 minutes or until a toothpick inserted into the center comes out clean.
Let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.