Place a round piece of parchment paper at the bottom of a 9-inch springform pan, then coat sides of pan and parchment paper with cooking spray.
In one bowl, combine egg yolks, lemon zest and 1/4 cup of sugar. Mix well with a spoon.
In a second bowl, combine the following dry ingredients: Almond flour, cardamom and baking powder. Add the dry ingredients to the egg yolk mixture and combine well. The mixture will be a bit tough to mix, but do your best to combine the ingredients as completely as possible.
Using a standing electric mixer, gently beat egg whites on low speed, then gradually increase to high speed. After 1 minute, add pinch of salt and teaspoon of vinegar and continue beating the egg whites. As the egg whites being to get whiter and soft peaks are just starting to form, slowly add 1/4 cup of sugar (a little at a time) until well combined. Continue beating the egg whites until stiff peaks form.
Gently fold the egg whites into the yolk mixture one scoop at a time. The mixture will be tough at first, but will loosen as you add more of the egg white mixture. Gently fold everything together until it's mostly uniform in color and texture.
Add batter to springform pan (I always add a piece of tinfoil under my springform pan to catch any leaks) and place in oven for 35 minutes.
Allow the cake to cool completely for at least 1 hour, or in the fridge overnight. To remove from springform pan, gently glide a knife around the perimeter of the cake, then release the pan sides. The cake should release easily if fully cooled.
Place the cake on a serving dish, sprinkle with powdered sugar, and surround with fresh organic blueberries and cut-up strawberries.