The old method of soaking the grated potatoes and onions in ice water for 5 minutes before wringing them out produces extra-crispy latkes, which are slightly more fragile, so you will need to increase the flour to ¼ cup if you use that method.
2 lb (1 kg) Yukon Gold potatoes, peeled
1 large onion
1 egg, beaten
2 tbsp all-purpose flour
½ tsp baking powder
Salt and freshly ground pepper
Vegetable oil for frying
Grate potatoes and onion in a food processor with the grating blade. Place in a towel and wring out excess moisture.
Combine potatoes, onions, egg, flour, baking powder, salt and pepper in a bowl.
Heat a thin layer of oil in a large skillet over medium heat. Spoon potato mixture into hot oil (about 2 tbsp for each latke) and flatten with a fork. The latkes will be irregularly shaped. Cook for about 3 minutes per side, or until well browned on both sides and crisp around the edges. Don't crowd pan. Drain well on paper towels. Cook remaining latkes, adding more oil as needed.
Reheat latkes in a 350°F oven for 5 minutes.