01 - Place grated raw potatoes in a clean kitchen towel and squeeze out excess liquid thoroughly.
02 - Mix grated potatoes, mashed potatoes, flour, baking powder, salt, and pepper in a large bowl.
03 - Add beaten egg and milk; stir until thick batter consistency forms.
04 - Melt 1 tbsp butter with 1 tbsp oil in large nonstick skillet over medium heat.
05 - Drop 1/4 cup batter portions into skillet; flatten gently with spatula.
06 - Fry 3–4 minutes per side until golden brown and crisp. Add remaining butter and oil as needed for subsequent batches.
07 - Transfer cooked pancakes to paper towels; serve hot with sour cream and fresh chives.