Preheat oven to 350°F (175°C). Grease and line a 9-inch cake pan.
Whisk flour, baking powder, baking soda, and salt in a medium bowl.
In another bowl, beat butter and sugar until fluffy. Add eggs and vanilla and mix well.
Mix in sour cream and vegetable oil until smooth.
Add the dry ingredients alternately with milk, beginning and ending with dry ingredients. Mix just until combined.
Gently fold in diced strawberries and strawberry puree.
Pour batter into the prepared pan and smooth the top.
Bake for 35–40 minutes, or until a toothpick inserted in the center comes out clean.
Let cake cool completely before frosting or topping with whipped cream.