Slice potatoes and put in medium bowl, cover with cold water
Mix flour, baking powder, salt, and pepper together in a separate bowl. Add milk and egg and stir batter until it is a smooth consistency. Let batter stand for roughly 20 minutes
Meanwhile, heat oil in a large pot or electric skillet to 350 degrees F (175 degrees C)
Take the potatoes out of the water and pat dry. Fry them in the hot oil until tender, roughly 5 minutes. Take out and drain on paper towels
Dredge the fish in batter, and place in the hot oil. Fry fish in batches until golden brown on all sides. Take out and drain on paper towels
Fry potatoes again in hot oil until crisp, 1 to 2 minutes, then take out and drain on paper towels
