Mix the dry ingredients: In a large bowl, whisk 2 cups all-purpose flour, 1 cup granulated sugar, 2 teaspoons baking powder, 1/2 teaspoon fine salt, and 1/2 teaspoon cinnamon. If using lemon zest, whisk in 1 teaspoon now.

Whisk the wet ingredients: In a separate bowl, whisk 2 large eggs, 3/4 cup milk, 1/2 cup plain yogurt or sour cream, 1 teaspoon vanilla, 1/4 cup melted unsalted butter, and 1/4 cup neutral oil until smooth.

Combine wet and dry: Pour the wet mixture into the dry ingredients. Gently fold with a spatula until just combined. The batter should be thick and slightly lumpy—do not overmix.

Prep the blueberries: Measure 1 1/2 cups frozen blueberries straight from the freezer. Toss them with 1 tablespoon flour to lightly coat.

Fold in the berries: Add the coated blueberries to the batter and fold gently a few times. Some streaking is normal—stop as soon as they’re fairly distributed.

Fill the muffin cups: Divide the batter evenly. Fill each cup almost to the top for tall, domed muffins. Sprinkle the tops with coarse sugar if you like.

Bake high, then lower: Bake at 425°F for 5 minutes. Without opening the oven, reduce the temperature to 350°F (175°C) and bake 14–17 more minutes, until the tops are golden and a toothpick comes out clean or with moist crumbs.

Cool briefly: Let muffins cool in the pan for 5 minutes, then move to a rack. Serve warm or at room temperature.