Prepare the Dough: In a large bowl, mix the whole wheat flour and salt. Gradually add water, kneading until you achieve a soft, smooth dough. Cover the dough with a damp cloth and let it rest for 20-30 minutes.
Prepare the Filling: Heat oil in a frying pan. Add cumin seeds and let them splutter. Add turmeric, red chili powder, garam masala, and coriander powder. Stir for 1 minute to release the spices' aromas. Add mashed potatoes and salt, and mix everything thoroughly. Let it cook for another 2-3 minutes. Optionally, stir in fresh chopped cilantro.
Assemble the Parathas: Divide the dough into equal-sized balls. Roll each ball into a small disc. Place a spoonful of filling in the center, fold the edges over, and pinch to seal. Roll the stuffed dough gently into a flat paratha.
Cook the Parathas: Heat a tawa or griddle over medium heat. Place the paratha on the tawa and cook until bubbles form on the surface. Flip it, apply oil or ghee on the cooked side, and cook the other side until golden brown and crispy.
Serve: Remove the paratha from the griddle and serve hot with yogurt, pickles, or chutney.