Preheat and prep: Heat your oven to 375°F (190°C). Line a 12-cup muffin pan with paper liners or lightly grease it.
Mix dry ingredients: In a large bowl, whisk together flour, baking powder, baking soda, and salt until well combined.
Rub zest into sugar: In a separate bowl, combine the sugar and lemon zest. Use your fingertips to rub the zest into the sugar until it smells fragrant and looks slightly damp.
This step boosts the lemon flavor.
Combine wet ingredients: Add eggs, Greek yogurt, oil, lemon juice, and vanilla to the lemon sugar. Whisk until smooth and creamy.
Bring it together: Pour the wet mixture into the dry ingredients. Stir gently with a spatula until just combined.
Stop when you no longer see dry streaks. A few small lumps are fine.
Prep the blueberries: Toss the blueberries with 1 tablespoon flour to help prevent sinking. Fold them into the batter very gently.
Fill the tin: Divide the batter evenly among the muffin cups, filling them about 3/4 full.
Sprinkle with coarse sugar if using.
Bake: Place the pan on the center rack and bake for 18–22 minutes, or until the tops are set and lightly golden and a toothpick inserted in the center comes out with a few moist crumbs.
Cool: Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. The crumb sets as they cool, so try to resist cutting in too early.