Preheat oven to 400F/200C/gas mark 6. Coat doughnut pan with cooking spray. Set two wire racks on the counter with waxed paper underneath them
Sift and measure the flours into a large bowl. Whisk or sift all the dry ingredients together (the sorghum flour through the cloves).
Put the flax seeds in a dry blender and grind them until they look like coarse flour. Add the ground flax seeds to the filtered water in a large mixing bowl (the bowl for a stand mixer if you have one) and let it stand five minutes.
Add the agave syrup, applesauce, coconut oil, and vanilla to the mixer bowl and blend until fluffy. You want to add as much air as possible to help create a tender, fluffy cake. With the mixer running on medium, add in the flour mixture a bit at a time until it is thoroughly mixed.
Add in the mineral water and mix just until you have a smooth, pourable cake-style batter.
Using a measuring cup or ice cream scoop, fill the doughnut depressions about half full. Use a spoon to smooth the batter around evenly. Wipe the top of the pan clean of drips and overspray.
Bake for 7-9 minutes.
Set the doughnuts on wire racks to finish cooling completely. If you need to reuse the pan, wipe it completely clean with a paper towel before spraying and refilling.
Glaze
Sift the cocoa powder with the powdered sugar into a small mixing bowl.
Adding just a small spoonful at a time, stir in the rice milk until you have a smooth, pourable glaze.
Drip the glaze over the doughnuts with a spoon, or place in a plastic bag, close the top, and cut off a small corner of the bag to make a disposable pastry bag.
Once the glaze has started to harden, sprinkle a few flakes of sea salt on each doughnut. If the salt crystals are very large, break them into smaller pieces with the back of a spoon before sprinkling.
Doughnuts are best if eaten on the first day, but can be left out on the counter for another day.