In a medium bowl, stir together the flour, sugar, baking powder, salt, and lemon zest. In a small bowl, stir together the lemon juice, oil, egg, and vanilla extract until the egg is well incorporated.
Pour the wet ingredients into the dry, and stir together gently until there are just a few pockets of flour remaining. Add in the blueberries, and stir together until there are no more dry pockets of flour. Let the batter rest at room temperature for about 20 minutes.
While the batter rests, preheat your oven to 425 degrees, and grease a muffin tin to prevent any sticking. Line with paper liners if desired in addition to greasing the tin. Scoop the batter evenly into your prepared baking tin. The batter will be thick, and should reach nearly the top of each muffin cup.
Sprinkle the tops generously with coarse sugar (or granulated if you don't have any coarse sugar) and bake for 16-18 minutes, or until golden brown and a toothpick comes out clean. Cool and enjoy!