Soak urad dhal for an hour. Drain water and grind it with green chillies very coarsely. Just run the mixer once or twice to make it coarse. Do not make it pastey. Set aside.
Steam the urad dal mixture for 7-10mins.Cool down and crumble it with your fingers, set aside.
Now heat oil, add mustard seeds let it crackle then add curry leaves, turmeric powder and hing.
Simultaneously boil water till it starts bubbling vigorously.
Add salt and boiling water to rice flour little by little and mix it with the help of a ladle. Mix it till it gathers to a smooth dough.
Allow it to cool for 2-3 mins then knead once with your hands to make a smooth dough but it will be slightly sticky. Keep aside.
Next add the coarsely grinded urad dhal green chilli mixture and saute until it becomes dry and raw smell completely leaves, it may take 7-10mins.
Add required salt. Then add coconut mix well and switch off. Now your inner stuffing is ready. Grease your hands with oil and make small lemon sized balls.
Then flatten it slightly thin (or make it as cup) then add a teaspoon of ulundu stuffing / filling and seal it as shown.
Repeat this until the entire dough finishes. This is the easiest method I am following till date :)
Press the ends and seal it completely and make the design by pressing your thumb. You can also make designs with fork or use readymade shapes.
Steam the kozhukattais for about 10-12mins or until the outer cover turns shiny which shows the kozhukattais are done. Enjoy Ulundu Kozhukattai!