In a medium saucepan, cover the Yukon Gold potatoes with cool water, season generously with salt and bring to a boil. Cook the potatoes until tender, about 15 minutes. Drain well and immediately pass the potatoes through a ricer into a large bowl.

Working quickly, peel and grate the baking potatoes on the large holes of a box grater into a medium bowl. Press with a clean kitchen towel to remove excess moisture. Add half of the grated potatoes to the riced potatoes.

Transfer the remaining grated potatoes to the bowl of a food processor. Add the onion and pulse until the potatoes and onions are very finely chopped. Transfer to a fine-mesh sieve and press with the back of a spoon to extract as much liquid as possible. Add the potato-onion mixture to the large bowl. Stir in the eggs, matzo meal, white pepper and 2 teaspoons of salt.

In a large, heavy skillet, heat 1/4 inch of oil until shimmering. Working in 3 batches, spoon 1/4 cup of the potato mixture into the oil for each latke; press slightly to flatten. Fry over moderate heat, turning once, until the latkes are golden and crisp on both sides, about 7 minutes. Drain the latkes on a paper towel-lined baking sheet and sprinkle lightly with salt. Serve with applesauce.