Peel and then grate the potatoes in your food processor. Transfer potatoes to a cheesecloth and twist cheesecloth into a pouch. Squeeze out the moisture. Set in a large bowl to allow starch to sink to the bottom. After about 10 minutes, carefully pour liquid from the bowl, reserving milky residue.
Mix eggs, potato starch, salt, and pepper into the milky residue. Add drained potatoes and onion and toss until evenly coated.
Heat oil over medium-high heat.Be careful not to let the oil smoke. Drop heaping tablespoonfuls of potato mixture into the pan and flatten them with the back of a spoon. Cook the latkes over moderately high heat until the edges are golden, about 2 minutes; carefully flip and cook about 2 more minutes. Drain on paper towels. Repeat with the remaining potato mixture. You can keep your latkes warm on a baking pan in the warm oven until you're ready to serve.
Peel your potatoes before grating them. I always remove potato skins since reading that potentially toxic glycoalkaloids which repel pests are concentrated in the skin of the potato.If you don't have a food processor, you can grate your potatoes by hand on the big round holes of your cheese grater (aka box grater).No potato starch? You can substitute with gluten free flour.Serve your latkes topped with velvety brown gravy, savory sour cream or sweet apple sauce.