Cook the sushi rice with water in a rice cooker or heavy-bottom pot until tender and sticky

In a small bowl, whisk rice vinegar with sugar and salt until dissolved, then fold this seasoning gently into the warm cooked rice

Spread the seasoned rice onto a tray or sheet pan and let it cool to room temperature, pressing lightly so the surface is even

Once cooled, cut the rice into evenly sized bite-sized cubes

Heat vegetable oil in a large non-stick skillet over medium-high heat until shimmering

Place rice cubes in the hot oil in a single layer and fry each side until golden brown and crispy, about 3–4 minutes per side

Transfer the crispy rice cubes onto a paper-lined plate to drain any excess oil

In a small bowl, whisk together Japanese mayonnaise, sriracha, and soy sauce to create the spicy mayo sauce

In a separate small saucepan, combine soy sauce, brown sugar, rice vinegar, and sesame oil over low heat, stirring until sugar dissolves to form the sweet soy glaze

Place a crispy rice cube onto a serving platter and lay a mango strip and cucumber slice over the top of each cube

Drizzle spicy mayo and sweet soy glaze over the mango and rice for layered flavor

Sprinkle toasted sesame seeds and add nori strips if using, for extra texture and umami

Serve with pickled ginger alongside as a refreshing palate cleanser