Wash the strawberries, remove the stems, and blend them into a purée. Strain if you want a smoother texture, then set aside.
Preheat the oven to 180°C (350–356°F) and prepare a 12-cup muffin pan.
In a bowl, mix the flour, baking soda, baking powder, and salt.
In another bowl, cream the butter and sugar until light and fluffy. Add the eggs one at a time, mixing well after each addition.
Add the yogurt and mix until smooth. Then gradually add the dry ingredients, mixing just until combined (don’t overmix).
Stir in the vanilla extract and about 2 tablespoons of the strawberry purée.
Divide the batter evenly between the muffin cups, filling them about 2/3 full. Add a small spoonful of strawberry purée on top of each and gently swirl with a knife.
Bake for 25–27 minutes, until a toothpick inserted in the center comes out clean. Let them cool completely on a rack.