Start by adding the sushi rice, sea salt, and water to a large pot.
Bring the pot to a boil, then turn the heat to low, cover, and let simmer until the rice has soaked up all of the water. This will take about 15-20 minutes on the stovetop.
In a small saucepan, combine the rice vinegar and sugar.
Cook over medium heat until the sugar has dissolved. Let this mixture cool.
In a 9x13 casserole dish, add the cooked rice. Stir the vinegar mixture into the rice until the rice is sticky. (It'll dry as it cools.)
Set aside, or cover and add to the refrigerator.