Preheat the oven to 350F and grease your donut pans with nonstick baking spray or spritz with oil. Set aside.
Add the freeze-dried strawberries to a high speed food processor or blender and pulse until they are a fine powder– about 45 seconds. Reserve 1 teaspoon of the strawberry powder for the glaze.
Add the remaining strawberry powder to a large bowl and whisk in the flour, sugar, and baking powder.
In a small bowl, whisk together the milk, vegetable oil, melted butter, egg, and vanilla.
Add the wet ingredients to the dry and mix just until combined-- you don’t want to overmix.
Divide the batter between the wells of the donut pan, filling each one with about ⅓ cup of batter. I like to use a piping bag but you could do this with a spoon as well.
Bake for 16-18 minutes, or until a toothpick comes out clean.
Transfer the donuts to a wire rack and allow them to cool completely before frosting.
(Optional) Whisk together the confectioner's sugar, milk, and the reserved teaspoon of the strawberry powder until smooth.
Dip the donuts in the frosting or spread the frosting over the top.
Store in an airtight container in the fridge for up to three days. Bring to room temperature before serving.