Preheat the oven to 350F, and line a muffin pan with liners.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

In the bowl of a stand mixer, beat together the butter, oil, and sugar until light and fluffy.

Add in the egg, beating until combined.

Add in the sour cream and vanilla, followed by the flour mixture. Mix until just combined, and don't over-beat! Finally, gently fold in the strawberry pieces and chocolate chunks

Divide the batter among the prepared muffin liners, and top each muffin with a couple more pieces of chocolate.

Bake for 25-30 minutes, until muffins are golden brown and puffy, and a toothpick inserted in the center comes out clean.