Preparing to bake: Heat the oven to 350 degrees F. Grease a 9- by 4-inch loaf pan.
Grating the zucchini: Grate the zucchini into a bowl. Put it in a double layer of paper towels. Squeeze the water out of the zucchini into the sink. This will help the zucchini bread to not be too wet. Set aside about 225 grams (or about 2 cups) of the drained zucchini.
Combining the dry ingredients: In a large bowl, combine the flour mix, psyllium, baking powder, soda, cinnamon, nutmeg, cardamom, and salt.
Combining the wet ingredients: Whisk together the egg, sugars, olive oil, yogurt, and vanilla extract.
Finishing the batter: Plop the drained zucchini into the liquids and whisk them together. Sprinkle the dry ingredients over the top of the liquids. Using a rubber spatula, fold the dry ingredients into the wet until no sign of flours remain.
Pour the batter into the prepared pan. Slide the pan into the oven and bake until the top of the bread is crackly brown and a toothpick inserted into the center comes out dry, 45 to 55 minutes.
Allow the bread to cool in the pan for 10 minutes. Turn it onto a cooling rack and let it cool to room temperature before slicing into it.
Pour all the flours into a large container. (Restaurant supply stores sell large plastic containers that fit this purpose well. You could also use a large glass jar.) Shake and shake and shake harder until all the flours have become one color.