01 - Preheat oven to 400°F. Line a 12-cup muffin tin with paper liners or grease thoroughly.
02 - Whisk together flour, baking powder, baking soda, and salt in a large bowl until well blended.
03 - In a separate bowl, whisk oil or melted butter, sugar, eggs, milk, and vanilla extract until smooth and fully combined.
04 - Pour wet ingredients into dry ingredients. Gently stir until just combined—batter should remain slightly lumpy. Avoid overmixing.
05 - Fold diced strawberries into batter until evenly distributed throughout.
06 - Divide batter evenly among muffin cups, filling each about three-quarters full.
07 - Sprinkle coarse sugar generously over the top of each muffin.
08 - Bake for 22 to 25 minutes until a toothpick inserted in the center comes out clean and tops are golden brown.
09 - Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.