Preheat oven to 325°F. Grease muffin cups or line with muffin liners.
Combine 1 1/2 cups flour, 3/4 cup 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.
To Make Streusel Topping: Mix together 1/2 cup sugar, 1/3 cup flour, 1/4 cup butter, and 1 1/2 teaspoons 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).
Pour enough batter so that it lines the edges of the muffin tops (it's about the same batter for a regular muffin). Sprinkle tops with streusel topping.
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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.