Prep the pan and oven. Heat the oven to 400°F (200°C). Line a 12-cup muffin tin with paper liners or lightly grease it. A hotter start helps create a tall dome.

Mix the dry ingredients. In a large bowl, whisk flour, sugar, baking powder, baking soda, salt, poppy seeds, and lemon zest until evenly combined. Rubbing the zest into the sugar with your fingers boosts lemon flavor.

Whisk the wet ingredients. In a separate bowl, whisk yogurt, milk, oil, eggs, lemon juice, and vanilla until smooth and well blended.

Combine gently. Pour the wet mixture into the dry. Stir with a spatula just until you see no dry streaks. The batter should be thick and slightly lumpy—do not overmix.

Portion the batter. Divide evenly among the muffin cups, filling each about 3/4 full. For a bakery-style dome, you can fill a bit higher.

Bake. Bake at 400°F for 5 minutes, then reduce the oven to 350°F (175°C) without opening the door. Continue baking 10–12 minutes more, until the tops are set and a toothpick comes out with a few moist crumbs.

Optional lemon syrup. While the muffins bake, warm lemon juice and sugar in a small pan until the sugar dissolves. Brush over the hot muffins right after they come out for added moisture and shine.

Cool and glaze (optional). Let muffins cool in the pan 5 minutes, then transfer to a rack. If using glaze, whisk powdered sugar with lemon juice to a drizzling consistency and spoon over cooled muffins.