Peel and halve the potatoes lengthwise, then place them in a bowl of cold water. This will help to prevent excessive browning.
Peel the onion and cut it into narrow chunks (that will fit into the chute for your food processor).
Prepare the egg replacer - making the equivalent of one egg - according to package instructions. Set aside to thicken.
Shred the potatoes and onion using your food processor with the shredding attachment. Place the shredded potatoes and onions onto a clean tea towel, hold the wrapped potatoes and onions over a bowl or the sink, and squeeze out as much liquid as you can.
Place the potatoes and onions in a large bowl. Add the prepared vegan egg and salt, and mix well.
Heat a large skillet over medium high heat, then cover the bottom of the pan with a thin layer of neutral oil that is appropriate for high heat.
Take a palm-sized scoop of the potato-onion mixture and form the latke with your hands, pressing gently, then carefully place the latke into the pan. Cook for several minutes, until you can see the edges darkening to a golden brown, then flip the latke and cook the other side. Repeat until you have used all of the potato-onion mixture.
Drain latkes on paper towels or on a cooling rack set over a baking pan. Serve warm.