In a small bowl, use a fork to whisk together the flaxseed and water to make a flax egg. Set aside for 10 minutes.
Preheat the oven to 350° F and grease and line two 8” round cake pans.
Puree the strawberries in a food processor or blender. Set aside.
In a large mixing bowl, whisk together the sugar and oil.
Add the flax egg, vanilla extract, strawberry puree, almond milk and apple cider vinegar. Whisk everything together until combined.
In a separate bowl, whisk together the flour, baking soda, baking powder, xanthan gum and salt.
Sift the flour mixture into the bowl wet ingredients. Stir or whisk until combined and no lumps of flour remain.
Distribute the batter evenly between the two cake pans and bake for 30-35 minutes, or until a toothpick inserted into the center of each cake comes out clean or with just a few moist crumbs.
Leave the cakes in their pans for about 10 minutes before transferring them to a wire rack to cool completely.