Rinse the sushi rice about three times, until the water runs mostly clear. Drain and combine with 1¼ cups water in a saucepan. Bring to a boil, cover, and reduce the heat to low. Simmer for 20 minutes. Remove from the heat and let stand, covered, for 10 minutes.

Combine the rice vinegar, brown sugar, and salt in a small saucepan. Warm gently, stirring until the sugar and salt dissolve. Set aside to cool.

Whisk together the shoyu, sesame oil, ginger, wasabi, and black pepper. Gently toss with the cubed ahi. Refrigerate while you finish the rice.

Fluff the cooked rice, then gently fold in the vinegar mixture. Let it cool for about 15 minutes.

Preheat your waffle iron thoroughly. Lightly brush the cooking surfaces with sesame oil. Add enough rice to form an even layer and gently press it down. Close the iron and cook until golden and crisp, about 5–10 minutes depending on your iron.

Transfer the crispy rice to a plate. Top with the marinated ahi, pineapple, and avocado. Finish with a sprinkle of furikake and serve immediately.