Rinse the sushi rice until the water runs clear. If time allows, soak it in water for 15 minutes before rinsing.
In a pot, bring 3 cups of water to a boil. Add salt and rice, then simmer covered for 20 minutes. Let it sit covered for an additional 10 minutes after turning off the heat.
In a bowl, combine rice vinegar, granulated sugar, and sesame oil. Microwave for 30 seconds or heat in a pot until the sugar dissolves. Pour over the rice and mix well. It should be sticky!
Line an 8x8 pan with plastic wrap and pack the rice tightly. Chill in the fridge for 1-2 hours or in the freezer for 30 minutes until cold and firm.
Once chilled, cut into squares or rectangles.