For the stuffing, wash sesame seeds well for 3 to 4 times in lots of water. (If using white, you can skip this step.
You have to remove all the impurities and spread it over a clean kitchen cloth. Let it be for 15 mins.
Mean while, for the dough, bring water to boil with a teaspoon of sesame oil and let it boil for a minute.
Add it to the flour with salt and mix well. Use a spatula for mixing. You may need more than double the times of water. So make sure you boil enough.
After it becomes warm, knead to a smooth dough and keep covered. You can make equal sized balls and keep covered.
By now the sesame seeds will be dry and roast it well until it pops.
Add jaggery and coconut to it and mix in low flame. As an optional step, you can grind the sesame seeds coarsely and proceed with the pooranam making.
Continue heating in medium flame until the jaggery melts and completely mixes.
When it starts leaving the sides, pour and cool down in a plate.
When it is still warm, make equal sized balls.
Make small cups and stuff the sesame inside. You can refer the VIDEO for help.
Steam it for 8 to 10 minutes. (water should boil before you place the kozhukattai inside the steamer).