Preheat the oven to 425°F (220°C). Line a 12-cup muffin pan with liners.
In a large bowl, whisk together flour, granulated sugar, brown sugar, baking powder, baking soda, and salt.
In a separate bowl, whisk the Greek yogurt, milk, oil, eggs, and vanilla until smooth.
Add lemon zest if using.
Pour the wet ingredients into the dry. Stir gently with a spatula until just combined. Do not overmix; a few small streaks of flour are fine.
Toss blueberries with a teaspoon of flour, then fold them into the batter with minimal strokes to prevent streaking.
Divide the batter evenly among the muffin cups, filling each about 3/4 full. Sprinkle tops with coarse sugar if you like.
Bake at 425°F for 5 minutes, then reduce heat to 350°F (175°C) without opening the oven.
Continue baking for 12–14 minutes, until the tops are set and a toothpick comes out with a few moist crumbs.
Cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. Enjoy warm or at room temperature.