Prep Muffin Tin: Preheat oven to 375 degrees F. Line a standard size muffin tin with liners, or grease well with non-stick cooking spray.

Combine Dry Ingredients: In a large mixing bowl combine the flour, sugar, salt, baking soda, and baking powder.

Mix Wet Ingredients: Add oil, egg, buttermilk, and vanilla and mix just until combined. Don't over mix (the batter doesn't need to be "smooth").

Add Blueberries: Toss the blueberries in a spoonful of flour. (Optional: helps them not to sink to the bottom of the muffin.) Gently fold blueberries into the batter. Divide batter between muffin cups.

Make Streusel: Make the crumb topping by adding all ingredients to a bowl. Use a fork or pastry blender to cut the butter into the mixture. Sprinkle topping over the tops of each muffin.

Bake for for 17-20 minutes, or until a toothpick inserted in the center comes out clean or with just a few crumbs. Remove muffins from oven and allow to cool in the pan for a few minutes before removing to a wire rack to cool completely.