Preheat oven to 200 degrees C. Grease 12 muffin cups or line with paper baking cups. Whisk together the flour, sugar, salt and baking powder in a large bowl.
Whisk vegetable oil, egg, milk and apple sauce together in a separate bowl until smooth then stir the liquid ingredients into the flour mixture until moistened. Lightly stir in the blueberries. Spoon the batter into the prepared muffin cups, filling them 2/3 full.
Bake muffins in the preheated oven until they rise and the tops are golden brown, about 20 minutes. A toothpick inserted into the centre of a muffin should come out clean.
We've also made these vegan with great success by using almond milk in place of regular and 1 tablespoon egg replacer and 1/4 cup water in place of the egg.