Preheat the oven to 400 degrees. Grease muffin tins or line with cupcake liners.
Combine flour, sugar, salt, and baking powder in a bowl. Add vegetable oil, milk, and an egg. Stir ingredients until just combined, being careful not to over stir. Gently fold in blueberries. Set batter aside.
In a separate bowl: Add brown sugar, flour, cinnamon and butter. Mix with a fork.
Portion batter into muffin tins (approx 12) and sprinkle crumb topping. Bake for 20 to 25 minutes or until set.