Preheat your oven to 350°F and lightly spray a donut pan with nonstick cooking spray.
In a large mixing bowl, whisk together the vegetable oil, buttermilk, eggs, sugar, salt, baking powder, and vanilla extract until fully combined.
Add the flour and stir until the batter becomes smooth.
Fold in the finely chopped strawberries gently using a wooden spoon.
Spoon or pipe the batter into the prepared donut pan, filling each cavity about 3/4 full.
Bake the Baked Strawberry Donuts for 17 minutes or until lightly golden and cooked through.
Remove the donuts from the oven and let them cool in the pan for 10 minutes.
Carefully remove the donuts from the pan.
Combine the sugar and cinnamon in a sandwich bag or shallow bowl.
Coat each donut lightly in the cinnamon sugar mixture.
Serve immediately or store in an airtight container.