Roast poppy seeds in a small skillet and let it cool. Grind it into a coarse powder and keep aside.
In a heavy bottom kadai, mix all the ingredients for stuffing except the poppy seed powder and let it sit for 15 mins.
Heat the mixture over medium flame for 10-12 minutes. When the mixture starts boiling, it will turn yellowish brown and sticky.
Take the kadai off the heat, add poppy seeds powder and mix well. Set it aside to cool down.
Preparation for cover:
In a vessel with tight-fitting cover, boil water and add salt and oil. Reduce the heat and slowly add the rice flour.
Start mixing vigorously with a heavy spoon. Now close the lid and take the pot off the heat. Let the covered pot cool down for 15 minutes.
With wet hands, mix the dough using cold water to keep the hands cold.
Boil water in a large vessel that can fit a steamer. Oil the steamer and set it aside.
Make about 20 balls of the dough and 20 parts of the stuffing. Make small puris with the dough ball on an oiled paper/aluminium foil. Keep one part of stuffing in the middle of the puri and gather the puri gently to shape it like a modak.
Dip each modak in cold water and place it in the steamer. Put the steamer on boiling water and cover it.
Let the modaks steam for 20 minutes on medium to high flame. Take the steamer off the vessel and let it sit for 5 minutes before removing the modak from the steamer.