01 - Rinse the sushi rice under cold water until the water runs clear. Combine rice and water in a saucepan, bring to a boil, reduce heat, cover, and simmer for 15 minutes. Remove from heat and let stand, covered, for 10 minutes.
02 - In a small bowl, mix rice vinegar, sugar, and salt until dissolved. Gently fold the mixture into the warm rice using a spatula. Cool the rice to room temperature.
03 - Preheat the waffle iron. Lightly grease the plates with a small amount of oil or nonstick spray.
04 - Spoon an even layer of seasoned sushi rice (about 1/2 cup per waffle) onto the waffle iron. Close and cook for 5–7 minutes, or until the rice is golden and crisp.
05 - Carefully remove the rice waffle from the iron and place on a plate. Repeat with the remaining rice.
06 - Top each rice waffle with slices of salmon, tuna, avocado, and cucumber. Drizzle with Japanese mayonnaise and soy sauce.
07 - Garnish with pickled ginger, nori strips, toasted sesame seeds, scallions, and a touch of wasabi if desired. Serve immediately for best texture.