Peel potatoes, then grate on the large holes of a box grater.
Rinse shreds briefly, then squeeze out moisture thoroughly using a clean towel.
Combine potatoes, grated onion, beaten eggs, flour, baking powder, salt, and pepper.
Stir in garlic and chives, if using, until the mixture just holds together.
Heat a slick of oil in a large skillet over medium to medium-high heat.
Scoop 1/4-cup portions into the pan and flatten to about 1/4 inch thick.
Fry until deeply golden, 3–4 minutes per side. Adjust heat as needed.
Transfer to a rack or paper towels; sprinkle with salt. Repeat, adding oil as needed.
Serve hot with applesauce or sour cream.