In a cup, steep the gyokuro leaves in 3 oz. of water, heated to 140°, for 1 to 2 minutes. Drain the leaves, and, if you like, steep the leaves a second time in the same amount and temperature of water for 30 seconds, then drain again.
In a small bowl, toss the spent tea leaves with the rice vinegar, soy sauce, and sesame oil until well combined. Serve over rice and garnish with sesame seeds.