Rinse sushi rice under cold water until water runs clear. In a pot, combine rice and water, bring to a boil, then simmer on low for 15 minutes. Keep covered for an additional 10 minutes.

Mix rice vinegar, sugar, and salt in a small bowl until dissolved. Fold this into the cooked rice gently to avoid mashing.

Spread seasoned rice in a shallow pan, pressing down evenly to about 1 inch thick. Cover and refrigerate for at least 4 hours or overnight.

Cut the chilled rice into squares. Heat oil in a non-stick pan over medium heat. Fry each square for 3-4 minutes per side until golden-brown.

Transfer fried rice squares to a plate lined with paper towels, serve plain or with toppings like spicy tuna or soy sauce.