Preheat your oven to 375°F (190°C) and line a muffin tin with paper liners.
In a large mixing bowl, whisk together the flour, sugar, baking powder, salt, and poppy seeds until evenly combined. This creates a light dry mixture that will help incorporate the wet ingredients smoothly.
In a separate bowl, whisk the egg lightly, then add the vegetable oil, lemon juice, vanilla extract, and lemon zest. Mix until the mixture is smooth and fragrant with a bright citrus aroma.
Pour the wet mixture into the dry ingredients and gently fold everything together with a spatula. Avoid overmixing; some lumps are fine—this keeps the muffins tender.
Evenly distribute the batter into the prepared muffin cups, filling each about two-thirds full. This allows room for the muffins to rise and develop that nice, domed top.
Bake the muffins for about 20 minutes, or until the tops are golden and a toothpick inserted in the center comes out clean. You'll hear a gentle sizzling or bubbling as they bake.
Remove the muffins from the oven and allow them to cool in the tin for 5 minutes, then transfer to a cooling rack. The tops should be crisp, and the interior moist with a tender crumb.
Once cooled slightly, enjoy these vibrant lemon muffins for breakfast or as a bright snack. Their aroma still lingers in the kitchen, promising fresh, tangy bites.