Rinse 1 pound of strawberries and slice the greens off. Add the strawberries to a food processor and purée until smooth. Measure 1 cup (use any excess purée in smoothies, yogurt, oatmeal, etc.).
Preheat the oven to 350 degrees Fahrenheit and spray 2 8” cake pans with cooking spray.
In a medium-sized bowl, whisk together the sorghum flour, oat flour, arrowroot starch, baking powder, and salt.
In an electric stand mixer bowl fitted with a whisk attachment, add the erythritol, egg whites, and egg. Mix on medium speed until the mixture is even. Then, add the strawberry purée, oil, almond milk, natural food coloring, stevia extract, strawberry flavor, and vanilla extract. Mix until the mixture is even.
Turn off the mixer and dump in the dry ingredients. Mix on medium speed until the mixture is even. Scrape down the sides of the bowl if necessary. Last, add the vinegar and mix until completely smooth.
Pour the batter into the prepared cake pans. Bake for ~30 minutes, or until the surface springs back when tapped.
Let cool slightly. Carefully run a knife or offset spatula around the cakes, then flip them onto wire cooling racks to cool completely. Use a very sharp, long knife (I used a 10” knife) to slice each cake into 3 or 4 layers.