Preheat the oven to 350°F and line a loaf pan with parchment paper.
In a large bowl, whisk together almond flour, coconut flour, psyllium husk powder, baking powder, and salt.
In another bowl, beat the eggs, olive oil, warm water, apple cider vinegar, and sourdough starter until combined.
Pour the wet ingredients into the dry and stir until a thick dough forms.
Spoon the dough into the loaf pan and smooth the top with a spatula.
Bake for 45 minutes or until the top is golden and a toothpick comes out clean.
Let the bread cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.