- 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.