Preheat the oven to 400 degrees. Spray a donut baking pan with cooking spray.
In a large bowl, stir together the flour, sugar (or sugar substitute), baking powder, and salt.
In a large measuring cup, pour in vegetable oil, milk, vanilla, and eggs, and stir together.
Pour the wet ingredients in the measuring cup into the dry ingredients in the large bowl.
Stir together until everything is smooth and there are no lumps.
Stir in chopped strawberries until evenly distributed.
Spoon the batter into each donut tin of the donut baking pan until about 2/3 full. You will either need two donut baking pans or will need to bake in batches.
Bake the donuts in a preheated oven at 400 degrees for approximately 10 - 12 minutes.
Turn the pan over to remove the donuts onto a cooling rack. Let cool for about 10 minutes.
Meanwhile, in a small bowl, make the glaze by stirring together the powdered sugar and milk.
Spoon the glaze over the donuts and serve.