Preheat the oven to 375°F (190°C) and line a muffin tin with paper liners. In a large bowl, whisk together the flour, sugar, baking powder, and salt.
In a separate bowl, whisk the milk, oil, egg, and vanilla extract until well combined. Gradually add the wet ingredients to the dry mixture, stirring until just combined.
Gently fold in the diced strawberries, ensuring they are evenly distributed without overmixing the batter.
Divide the batter evenly into the muffin cups, filling each about ¾ full. Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean. Let them cool for a few minutes before enjoying!