01 - Place the grated raw potatoes in a clean tea towel and squeeze out as much moisture as possible, wringing tightly until dry.
02 - In a large bowl, combine the grated raw potatoes and mashed cooked potatoes, mixing thoroughly.
03 - Add the flour, baking powder, salt, and black pepper to the potato mixture. Mix well until evenly distributed.
04 - Gradually stir in the milk to form a thick, slightly lumpy batter. Do not overmix.
05 - Heat 1 tablespoon butter and 1 tablespoon oil in a large nonstick skillet over medium heat until the butter foams slightly.
06 - Drop large spoonfuls of the batter into the pan, flattening gently with the back of the spoon to form pancakes about 1/2-inch thick.
07 - Cook for 3 to 4 minutes per side, until golden brown and crisp. Flip carefully when the edges appear set.
08 - Repeat with remaining batter, adding more butter and oil as needed to maintain the frying medium.
09 - Drain pancakes briefly on paper towels to remove excess oil. Serve hot, topped with a dollop of sour cream and a sprinkle of chives if desired.