Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners.
In a large bowl, whisk together the flour, sugar, baking powder, and salt.
In another bowl, mix the vegetable oil, egg, milk, lemon zest, and lemon juice until well combined.
Pour the wet ingredients into the dry ingredients and gently stir until just combined.
Using a scoop, distribute the batter evenly among the muffin cups, filling each about 2/3 full.
Bake in the preheated oven for 18-20 minutes, or until a toothpick comes out clean.
Remove from the oven and let cool in the pan for 5 minutes.
Transfer muffins to a wire rack to cool completely.
Dust with powdered sugar before serving, if desired.