Preheat your oven to 400 F and line a muffin pan with muffin liners. You can grease the muffin cups if you are not using liners
In a medium bowl, whisk together 1 ½ cups all-purpose flour, ¾ cup granulated sugar, ½ tsp salt, and 2 tsp baking powder until combined
In a small bowl or glass measuring cup, whisk together 1/3 cup vegetable oil, 1 egg, and 1/3 cup milk until combined
Using a rubber spatula, fold the oil mixture into the flour mixture until just a few streaks of flour remain
Fold in the 1 cup blueberries until just combined
Make the crumb topping by mixing the ½ cup all-purpose flour, ½ cup granulated sugar, ¼ cup cubed butter, and 1 ½ tsp ground cinnamon. Use a fork to break up the cubes of butter
Spoon the batter into the muffin tin, filling each one to the top
Sprinkle the crumb topping generously over each muffin
Bake for 20-25 minutes or until a toothpick inserted in the center comes out clean