Wash rice and soak in water for about 1 hour. Drain well and reserve for later use.
Wash sesame seeds and drain well. Heat in pan withOUT any oil and fry until fragrant and dry.
Place rice, sesame seeds and 3 cups of water in blender and blend into smooth paste.
Pour paste into soup bag, and squeeze out juice.
Put juice into saucepan, heat and stir. Add in the remaining 3 cups of water, stirring constantly. Add in rock sugar and cook until melted.