Wash the rice thoroughly until the water remains clear. Bring rice and 75 ml water to the boil in a closed pot. Turn off the heat and let the rice swell for 20 minutes. Remove the pot from the heat and let the rice steam for another 20 minutes in the open pot.
Season rice with vinegar, salt and sugar, place on a tray and allow to cool. Cut seaweed leaves crosswise into eight strips. Shape some rice into an oval. Place them on the work surface and wrap one seaweed strip around each, pressing the end slightly.
Rinse the caviar briefly in ice-cold water and let it drip off. Immediately before serving, add 1-2 teaspoons of caviar to each rice.