To a bowl, add maida. Add turmeric powder, oil and water to make an elastic dough. Cover the dough and keep it aside for 30 minutes.
In a pan, dry roast the channa dal until aromatic and soak in water for an hour. After an hour, pressure cook the dal. The dal should not turn mushy. Mash it and keep aside.
Add the grated jaggery and channa dal to a pan (preferable non stick). Keep stirring. The mixture will be watery in the beginning. As the jaggery starts cooking it will turn thick and begin to turn into a halwa consistency.
Add cardamom to the channa dal jaggery mixture and let it cool completely. Once cooled, make lemon sized balls and keep aside. This is the Pooranam (filling).
Take a little of the kneaded maida dough. Place the filling and cover it completely with the dough.
Use a well oiled banana leaf or a parchment paper, Place the ball on the oiled surface and start making poli. You should press from the centre and proceed to the end to make a thin poli.
Heat a skillet, place the prepared poli and cook on both sides with ghee. Serve hot.