In a mixing bowl, add all-purpose flour, cornflour, baking powder, salt, and pepper. Mix well.
In another mixing bowl, add 1/2 cup water, egg, and oil. Mix well.
Then pour the wet ingredients into the dry ingredients bowl. Mix thoroughly. If needed then add 1 tbsp water. The batter should not be too thick or too thin. It should of coating consistency.
Heat oil in a wok. Drop batter into the oil and if it comes to the top within 1 or 2 seconds then it means the oil is ready.
Dip the stuffed potatoes into the batter. Make sure it is well coated. Then drop it into the oil. Fry the potatoes on medium heat till it becomes golden yellow in colour.
Take it out and allow it to cool down.