Peeled and grated the raw potatoes using a box grater or food processor. Place the grated potatoes in a clean kitchen towel and squeeze out excess moisture.

In a large mixing bowl, combine the grated potatoes, mashed potatoes, flour, baking powder, salt, and black pepper. Mix well.

In a separate bowl, whisk together the egg and buttermilk until combined. Pour the wet mixture into the dry ingredients and stir until just combined.

Heat 1 tablespoon of vegetable oil in a large skillet over medium heat. Once hot, drop 1/4 cup of the batter into the skillet for each pancake, flattening slightly with the back of a spatula.

Cook for about 3-4 minutes on each side, or until golden brown and crispy. Add more oil as needed for subsequent batches.

Transfer the cooked pancakes to a paper towel-lined plate to drain excess oil. Repeat with the remaining batter.