Peel potatoes. Grate potatoes and onion on the large holes of a box grater.
Squeeze out moisture. Wrap the grated mixture in a clean towel and wring until very dry.
Whisk eggs in a large bowl. Stir in flour, baking powder, salt, pepper, and garlic powder.
Fold in the dried potatoes and onion until evenly coated and sticky.
Heat a generous slick of oil in a large skillet over medium to medium-high heat until shimmering.
Scoop 1/4-cup mounds into the pan. Flatten gently. Fry 3–4 minutes per side until deep golden.
Transfer to a rack or paper towels. Sprinkle with a pinch of salt while hot. Repeat with remaining batter.
Serve immediately with sour cream and applesauce.