Peel the sweet potato, beet, and onion. Grate all three on the large holes of a box grater into one large bowl. Wear gloves for the beet if you would rather not stain your hands.

Toss the shreds with the kosher salt and let them sit 10 minutes.

Tip the shreds into a clean kitchen towel, gather the corners, and twist hard over the sink until the liquid stops running. Return the shreds to the dry bowl and fluff them apart.

Pour the beaten eggs over the shreds, then add the matzah meal, potato starch, garlic powder, and black pepper.

Fold everything together until no dry pockets remain and let it rest 2 minutes. Fry within 15 minutes of mixing.

Pour the oil into a heavy skillet to a depth of about ¼ inch and heat it to 350F. A single shred dropped in should sizzle at once.

Drop scant ¼ cup mounds into the oil, three or four at a time, and press each one flat with the back of a spoon to about 3 inches across.

Fry 3 to 4 minutes per side, until the edges are deep and lacy and the surface is set. Let the oil return to temperature between batches.

Move the latkes to a wire rack, not paper towels, and salt them immediately while they are still hot.

Serve hot with chilled applesauce and sour cream, with the chives scattered over the sour cream.