Scallion Potato Pancakes

1. Set a wire rack inside a rimmed baking sheet, and line rack with paper towels; set aside. Thinly slice light green and dark green parts of scallions to equal 2 loosely packed cups; set aside. Reserve remaining scallions for another use.

2. Insert shredding disk in a food processor (or use large holes of a box grater over a medium bowl); shred potatoes and onion. Working quickly and in batches, place shredded potatoes and onion on a clean kitchen towel, and squeeze firmly over sink to remove as much liquid as possible. Transfer potatoes and onion to a large bowl. Add thinly sliced scallions, eggs, potato starch, cake flour, 2 teaspoons salt, baking powder, five-spice powder, and pepper; stir until combined.

3. Pour oil to a depth of 1/8 inch in a cast-iron skillet; heat over medium until shimmering. Working in batches of 3, spoon 1/4 cup potato mixture for each pancake into hot oil. (Potato mixture should sizzle as soon as it hits the oil.) Using a metal or heat-resistant spatula, press to flatten. Cook over medium until edges and bottoms are browned and crisp, 3 to 5 minutes. Sprinkle each pancake with a pinch of salt and a pinch of sesame seeds. Flip and cook until browned and crisp, 2 to 3 minutes. Transfer to prepared wire rack. Serve with sour cream.

Alternative Method

1. To make 2 large scallion potato pancakes, Prepare recipe as directed in Steps 1 and 2. Omit Step 3, and instead: Heat 1/4 cup of the oil in a 12-inch cast-iron skillet over medium-high until shimmering; add half of potato mixture (about 2 1/2 cups). (Potato mixture should sizzle as soon as it hits the oil.) Using a metal spatula or heat-resistant spatula, press potato mixture into an even layer to cover bottom of skillet. Reduce heat to medium. Cook, turning skillet 90 degrees every 2 minutes, until bottom of potato mixture is crisp and browned, 8 to 10 minutes. Sprinkle evenly with 1 teaspoon of the sesame seeds and 1/4 teaspoon of the salt. Slide potato pancake onto a large plate. Place a second large plate on top, and invert.

2. Add 2 tablespoons of the oil to skillet, and reduce to medium heat. Slide potato pancake, uncooked side down, back into skillet. Cook, turning skillet 90 degrees every 2 minutes, until bottom is crisp and browned, 6 to 8 minutes. Slide potato pancake onto prepared wire rack.  Repeat cooking procedure with remaining potato mixture, 6 tablespoons oil, 1 teaspoon sesame seeds, and 1/4 teaspoon salt. (If liquid collects at bottom of bowl before adding potato mixture to hot skillet, squeeze liquid from potato mixture before cooking.) Serve with sour cream.