Mix the flour, salt and oil. Add warm water gradually and knead into a soft, smooth dough. Cover and rest for 20 minutes.
Mix all stuffing ingredients in a bowl. The mashed potatoes must be completely cool and dry.
Divide the dough into 8 equal balls. Roll one ball into a small disc, place 2 tablespoons of stuffing in the centre, and gather the edges up and over to seal like a dumpling.
Flatten gently, dust with flour, and roll out to a 7-inch circle with even pressure.
Heat a tawa over medium-high heat. Place the paratha on it and cook 30 seconds until bubbles appear. Flip.
Spread half a teaspoon of ghee on top, flip again, and press gently. Cook until both sides have golden-brown spots, 1–2 minutes per side.
Repeat with remaining dough and stuffing. Serve hot with butter, curd and pickle.