Using a box grater or a rotary grater or a food processor, shred the potatoes and the zucchini.
If you haven't been able to thinly slice the onion with a knife, then grate the onion as well.
Mix all the vegetables together and sprinkle with about 1 tsp of Kosher salt. Toss everything together and let it sit for about 5 mins to draw out as much liquid as possible.
While the shredded vegetables are resting, pour about 1/2" of oil into a frying pan or a large pot (I like to use my cast iron skillet). Set it over medium-high heat and let it come up to about 360°-375°F. While the oil is heating:
Scoop the vegetables into a square of muslin cheesecloth or a clean cotton dishcloth and wring out as much moisture as you can. Let it rest for a couple of mins and squeeze again. You want the shredded vegetables to be as dry as you can get them.
Once you've squeezed out as much liquid as you possibly can, return the mixture to the (emptied dry) bowl and toss with the almond flour, the egg, and the black pepper. I find it easiest to use my hand to mix to make sure everything is well incorporated. Keep an eye out for clumps of the almond flour as you're mixing and break those up.
If your oil has come up to temperature, now is the time to fry! Scoop out 2 tbsp of the shredded mixture and form into a loose, flat-ish disk. Do NOT make your latkes larger than 2 tbsp worth of the mix, otherwise they'll be too thick and won't cook through the middle.
Lay them gently in the oil and let them cook until the edges start to turn a light brown. Then using a spatula or a spider, flip them over and let them cook a few more mins. Check and see how they're browning and remove them from the oil when they're a toasty brown color. (Remember that they'll get a little deeper, darker brown as they cool.)
Place them on a wire rack to drain and cool slightly (or some doubled paper towels if you don't have wire racks). Sprinkle with a little Kosher salt while they're still hot and fresh out of the oil, if you want.
Serve with the usual latke accompaniments or use these as the base for an absolutely delicious version of eggs benedict or with some smoked salmon and dill.