Instructions

1. 1
   Preheat oven to 400°F (204°C).
2. 2
   Grease a 12-cup muffin tin or line with paper liners.
3. 3
   Whisk flour, sugar, salt, and baking powder together in a large bowl.
4. 4
   Pour vegetable oil into a 1-cup measuring cup.
5. 5
   Add the egg and fill the remainder of the cup with milk.
6. 6
   Whisk to combine, then pour into the dry ingredients.
7. 7
   Fold the batter together gently with a fork until just combined (it will be thick and slightly lumpy).
8. 8
   Fold in the blueberries gently.
9. 9
   Divide the batter evenly among the 12 muffin cups.
10. 10
    Make streusel: Mix sugar, flour, butter, and cinnamon with a fork until crumbly.
11. 11
    Sprinkle a generous tablespoon over each muffin.
12. 12
    Bake for 15 to 20 minutes, or until a toothpick inserted in the center comes out clean.
13. 13
    Cool on a wire rack.