Make the Muffin Batter:

1. Preheat oven to 425°F (218°C). Line a muffin pan with 6 paper liners. Use alternating spaces in the liners- space out the liners so that no two are directly next to each other. This allows the muffins to rise higher. Set aside.
2. In a medium bowl, use your hands to rub the lemon zest and granulated sugar together until the mixture is combined and fragrant. This releases extra lemon flavor. Whisk in the flour, baking powder, and salt. Set aside.
3. In a large bowl, whisk the oil, sour cream, milk, egg, and vanilla until combined.
4. Add the dry ingredients to the wet ingredients and gently fold together, making sure not to over mix. Fold in the blueberries, reserving about a handful for topping. The batter will be thick and lumpy.
5. Set aside the batter for at least 10-15 minutes, or cover it with plastic wrap and refrigerate for up to a day.
6. Divide the batter between the 6 liners, filling it all the way to the top. Dot the reserved blueberries on top and sprinkle with coarse sugar, if using.
7. Bake muffins for 5 minutes at 425°F (218°C). After 5 minutes, lower the oven temperature to 350°F (177°C) and bake for another 14-18 minutes. The muffins are done when a toothpick inserted in the center comes out clean or with moist crumbs.
8. Remove muffins from the oven and allow to cool in the pans for 5-10 minutes as you prepare the glaze.
9. In a small bowl, mix the powdered sugar and lemon juice until combined. Add extra powdered sugar for a thicker glaze or an extra squeeze of lemon juice for a thinner glaze as necessary.
10. Drizzle the muffins with the glaze and serve warm. You can drizzle the glaze using a spoon, a squeeze bottle, or a plastic bag with the corner snipped off.