Line a 9″ x 5″ glass loaf pan with parchment paper. Set aside.
Preheat the oven to 350 degrees.
Place 4 tablespoons of ground golden flax meal into the bowl of a stand mixer. Stir in 1/2 cup warm water. Allow this mixture to sit for at least 5 minutes so the flax can absorb the water.
Wash and dry 2-3 large lemons. I prefer to use organic lemons for this. Zest enough lemon to yield 2 tablespoons of fresh zest. Place into the bowl with the flax meal.
Juice enough fresh lemons to yield 1/2 cup of fresh juice. You will likely need 3-4 large lemons (use the lemons that you just zested). Place the strained juice in a small saucepan. Reduce the liquid to half to yield 1/4 cup. You will need to watch the pan to prevent burning. The liquid will evaporate quickly. Adjust to prevent burning. Place the juice into the bowl of stand mixer fitted with a paddle attachment.
Add in 1/2 cup of mild oil. You can use canola, avocado, vegetable, or even light olive oil. I do not recommend using coconut oil. I’ve tested this recipe with it, and the end product is very heavy and oily.
Add in 1/4 cup of unsweetened coconut or almond milk (the refrigerated kind).
Add in 1/2 cup granulated sugar and 1/2 cup sifted powder sugar. Using some powdered sugar is important because it usually contains some corn or potato starch. This starch will help to bind our ingredients together.
Mix all of the above ingredients together until smooth.
Add in 2 cups of gluten free flour blend with xanthan gum. I used King Arthur’s Measure for Measure in this recipe.
Add in 2 teaspoons of baking powder, 1 teaspoon of baking soda, and 1/4 teaspoon sea salt. Mix together until the wet and dry ingredients just come together. Do not over mix.
Place 1 cup of fresh blueberries into a bowl. Stir in 1 teaspoon of water or lemon juice. Add 1 tablespoon of gluten free flour. Toss together to coat the berries. Add to the mixing bowl. Stir until the berries are just incorporated evenly in the batter.
Add 2 tablespoons of apple cider vinegar to the batter. Place the mixer on low and mix just until the vinegar is incorporated into the batter.
IMMEDIATELY transfer the batter into the prepared loaf pan. Try not to stir. I like to tip the bowl over the loaf pan on an angle and use a silicone spatula to push the batter into the pan. You can gently smooth the top of the pan if you’d like. I also like to press a few blueberries into the top of the batter.
Bake for 60-60 minutes or until a cake tester inserted into the center of the cake comes out clean. If you find that the top of you cake is browning too much, you can loosely cover the loaf pan with foil. By loosely, I mean literally laying a piece of foil over the top without cinching the sides.
Once cooked, you MUST allow the cake to cool completely before serving. If you cut into the cake too early you’ll have a mess and it will likely be gummy. I like to make this cake at night. I leave it on the counter or stove top all night to cool. It is literally perfect the next morning. This cake is also incredibly delicious served cold.