Preheat oven to 400°F (200°C) and line a 12-cup muffin tin with paper liners. Whisk together the flour, poppy seeds, baking powder, baking soda, and salt in a large bowl.

In a separate bowl, whisk the eggs and granulated sugar for 1 minute until pale, then whisk in the oil, sour cream, vanilla extract, and lemon zest until smooth.

Pour the wet ingredients into the dry and fold with a spatula until just combined, about 12 to 14 folds. Stop as soon as no dry streaks remain.

Divide the batter among the muffin cups, filling nearly to the top. Sprinkle the coarse sugar evenly over each muffin.

Bake for 18 to 20 minutes until the tops are golden brown and a toothpick inserted in the center comes out clean. Cool in the tin for 5 minutes, then transfer to a wire rack and serve warm.