Make Japanese rolled egg and cut into small cubes(if you can not make rolled egg, the egg can be just fired flat and sliced into thin strips instead).
Cut sashime grade tuna into cubes.
Cut Australian avocado into cubes and set aside.
Make sushi vinegar. Put all sushi vinegar ingredients into a small saucepan and bring it to boil over medium heat. Turn the hear off and let cool.
Put 100ml of the water that the mushroom soaked in and 2 tbs of sugar, 2 tbs sake, and 2 tbs of soy sauce into a saucepan.
Put the sliced mushrooms and carrots into the sauce pan and bring it to boil then reduce the heat to low and allow it to simmer until the most of the liquid has reduced and the carrots are soft.
Remove from heat and allow to cool down
When the rice is cooked, pour the sushi vinegar over the rice and mis using a cutting action with a wooden spatula.
Serve 1/4 of the rice on a plate and scatter all toppings prepared previously. Garnish with thinly slice Shiso leaves and Nori sheet pieces.
Notes
If you don't have wild rice, replace with sushi rice and if you don't know how to prepare sushi rice(vinegared), check How to make perfect sushi rice post.