Soak jaggery in warm water(till immersing level) , crush it well. Then heat it up until it is slightly thick (no string consistency needs to be checked).Strain and keep aside. (I made more than above mentioned quantity for storing purpose).
In a mixing bowl add rice flour, salt and mix well. Boil water and add it little by little.
Mix with a ladle, once it forms together and is a bit warm to handle then use your hands to knead it a soft dough. Do all this off the stove. Keep this covered with a wet cloth to avoid drying while you do make the stuffing.
Rinse sesame and strain it well. Let it dry for a while. In a pan dry roast sesame till it pops out. Don't let it burn. Set aside.
Now take the jaggery syrup and heat it up till it becomes honey like in consistency. Now add roasted sesame and coconut.
Keep cooking till it forms a thick stuffing, it will easily leave the sides of the pan but will be sticky. Set aside to cool.
Now from the prepared dough pinch a lemon sized balls and roll it to a ball.
Flatten it thin and press in the center to make a dent, it should be like a small cup as shown below. Now take a generous spoon of sesame filling and place it in the middle. Bring the edges to the center.
And seal it in the form of a modak. Likewise make all the modaks and keep it ready. Steam it for 10mins or until they turn shiny and look cooked.
Serve Ellu Kozhukattai hot / warm!