Preheat oven to 400°F (200°C). Grease muffin cups or line with muffin liners.
To make the muffin batter, combine the flour, sugar, salt and baking powder. Place vegetable oil into a 1 cup measuring cup; add the egg and enough milk to fill the cup. Mix this with flour mixture. Fold in blueberries. Fill muffin cups about 2/3 full.
To make the streusel topping, Mix together the sugar, flour, butter, and cinnamon. Mix with fork, and sprinkle over muffins before baking. (I mixed with fork and then mixed with my hands, pressing the mixture together and then rubbing it between my fingers to make it crumbly).
Bake for 20 to 25 minutes in the preheated oven, or until done.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.