Dry roast the sesame seeds till it releases the aroma then cool it down and make fine powder from it.
Add grated or powdered jaggery, cardamom powder in sesame powder and blend it well, then make small balls from it.
Heat water and bring it to boil, add rice flour in it and stir it well, then cover and keep it a side.
Knead dough well to make crack free dough and make 11 (eleven) equal size of balls from dough, roll puri from it.
Put balls made from blended mixture at centre of puri and bring all edges together and give modak shape to it.
Steam modak a steamer for 8-10 minutes and serve it hot or cold as you wish.