Preheat the oven to 325 degrees F, sprinkle three 6-inch cake pans** with non-stick spray, and line them with circles cut from parchment paper.
Pulse the freeze-dried strawberries to a fine powder in a food processor, mini-chopper, or blender.
Place the cake flour, all-purpose flour, sugar, baking powder, baking soda, salt, and strawberry powder in the bowl of an electric mixer, and stir on low speed to combine.
Add the butter, mixing on medium-low speed until the mixture resembles damp sand (about 1 minute.
Add the eggs, one at a time, scraping the bottom and sides of the bowl to be sure all of the ingredients are fully incorporated.
Add the sour cream, milk, lemon zest, and vanilla.
Mix on medium speed for 2 to 3 minutes, to aerate the batter and build the cake's structure.
Divide the batter equally between the prepared pans, and bake for 30 to 40 minutes, or until a toothpick inserted in the thickest part of the cake comes out clean or with a few moist crumbs.
Cool completely before filling and frosting.