Take the flour in a bowl, knead with water and a splash of cooking oil. Be careful with the water quantity - you do not want your dough to be soggy. The dough needs to be of a consistency where it doesn't stick to your finger.
Cover the dough with a moist cloth.
In the meantime, peel the mangoes, chop into small cubes, add the mango-ginger, black pepper and mix very lightly. Keep aside.
Make small round balls of the dough, roll them to flat circles about 4-5 inches in diameter. Add 1 tbsp of the mango mixture and carefully fold to a semi-circle with the edges coming together. Use your fingers or a fork to crimp the dough along the edges thereby sealing the wrapper.
Heat the oil in pan and deep fry the pulis till golden brown.
Serve the hot pulis with the sauce.