Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners.
In a large bowl, mix the flour, sugar, baking powder, baking soda, and salt.
In another bowl, whisk together the egg, buttermilk, vegetable oil, lemon zest, and lemon juice.
Pour the wet ingredients into the dry ingredients and stir until just combined.
Fill each muffin cup about two-thirds full with the batter.
Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the pan for 5 minutes.
Transfer the muffins to a wire rack to cool completely.
Enjoy your freshly baked lemon muffins!