Step 1: Preheat & Prepare Muffin Pan
Preheat oven to 375°F (190°C).
Line a 12-cup muffin tin with paper liners or grease with non stick spray.
Step 2: Mix Dry Ingredients
In a large bowl, whisk together flour, sugar, baking powder, baking soda, and salt.
Step 3: Mix Wet Ingredients
In another bowl, whisk eggs, oil, buttermilk, vanilla extract, lemon zest, and lemon juice until combined.
Step 4: Combine Wet & Dry Ingredients
Gently mix the wet ingredients into the dry ingredients until just combined (do not overmix).
Step 5: Fold in Blueberries
Toss blueberries in 1 tablespoon flour (to prevent sinking), then gently fold them into the batter.
Step 6: Fill Muffin Cups
Divide batter evenly among the 12 muffin cups, filling about ¾ full.
Sprinkle with coarse sugar or streusel topping (optional).
Step 7: Bake the Muffins
Bake for 18-22 minutes, or until a toothpick inserted in the center comes out clean.
If using frozen blueberries, bake 1-2 minutes longer.
Step 8: Cool & Serve
Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.