Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners.
In a large bowl, whisk together the flour, sugar, poppy seeds, baking powder, baking soda, and salt.
In another bowl, combine the buttermilk, vegetable oil, egg, lemon zest, and lemon juice.
Pour the wet ingredients into the dry ingredients, and mix until just combined.
Do not overmix; it's okay if there are a few lumps.
Divide the batter evenly among the muffin cups, filling each about 2/3 full.
Bake for 18-20 minutes or until a toothpick inserted comes out clean.
Allow the muffins to cool in the pan for 5 minutes, then transfer them to a wire rack.
If desired, drizzle with lemon glaze once cooled.
Enjoy your freshly baked muffins warm or at room temperature!