1 ¾cupblueberries(245g) (fresh or frozen will work, if using frozen you do not need to thaw first, and note that they may leave purple streaks through your muffins).
Coarse sugar for sprinklingoptional (may just use regular granulated sugar or omit entirely).
Preheat oven to 425 (215C) and line a 12 count muffin tin with paper liners.
In a medium-sized bowl, whisk together flour, sugar, baking powder, baking soda, cornstarch, salt.
In a separate bowl whisk together butter and canola oil. Add egg and vanilla. Stir in sour cream until thoroughly combined.
Add wet ingredients to dry and gently fold together with a spatula until mostly combined. Once the batter is about 75% combined, add the blueberries and fold them in as well until batter is completely combined (don’t over-mix!).
Evenly divide muffin batter into prepared tin. Liners will be most of the way full!
Transfer to 425F (215C) preheated oven and bake for 8 minutes. After 8 minutes reduce the oven temperature to 350F (175C) without opening the oven door and then continue to bake another 10-12 minutes or until the tops are beginning to turn golden brown and a toothpick inserted in the center comes out clean or with a few moist crumbs.
Allow to cool 10 minutes in muffin tin then gently remove from pan (I like to use a butter knife to gently pry the muffin out of the tin, remember the pan may still be hot and muffins are fragile when they are warm!) and allow to cool completely on a cooling rack (otherwise muffin bottoms may become soggy).
Store in an airtight container at room temperature for up to 2 days. Muffins may also be frozen for several months. Refrigerating will dry out the muffins and I do not recommend it.
Making as jumbo muffins:
Divide batter evenly into a 6-count jumbo muffin tin. Bake on 425F (220C) for 8 minutes then reduce the oven temperature to 350F (175C) (do not open oven door) and bake another 13-15 minutes or until tops are beginning to turn golden brown and a toothpick inserted in the center comes out clean or with a few moist crumbs.