Mix the sushi seasoning (for mixed vegetable chirashi sushi) into the warm rice, then gently fold in the simmered vegetable mix from the kit.

Slice the cucumber into thin rounds. Boil the edamame in plenty of salted water (not included in ingredient list), or thaw if using frozen, then remove the beans from the pods.

Line a 6-inch (15 cm) round cake pan with plastic wrap. Spread half of the rice mixture from step 2 in the pan, sprinkle with the edamame from step 3, then cover with the remaining rice mixture.

Once the sushi cake has set and holds its shape, lift it out of the pan using the plastic wrap and place it on a serving plate.

Arrange the sliced cucumber, omelet pieces, and sushi toppings (such as sashimi) around the outside of the cake.

Decorate the center with more sliced cucumber, shrimp, and salmon roe for color, then scatter the star-shaped omelet pieces on top.