You cannot just use raw fish from the supermarket.It would be dangerous to do so.Sushi restaurants freeze the portions for several days at low temp to kill any parasites and then thaw.
Tuna can sometimes be found as sushi or sashimi grade but you will pay a price still have only one kind of fish.
We make alot of sushi at home but none of it is raw.
make your rice according to a sushi rice recipe.
We roll our sushi on a quart size zip=lock baggie since I don't have a mat and it works just fine.
See you-tube videos for technique and rice quantity.
Some ofthe ingredients we mix for home sushi are;
(for spicy roll)
Cooked shrimp chopped with some sri hacha chili sauce.
(for creamy roll)
Cooked shrimp chopped fine add a little mayo,splenda,soy
Fake crab legs,avacado, cucumber,sesame seeds.
(cut cucumber to same length as nori wrapper)
(can roll on either side of nori with rice applied)
smoked salmon and a little cream cheese can add a green onion too.
Other ingredients to try too.
whole cooked shrimp
cooked salmon or any fish
julienne carrot,green onion,daikon
I always make these mussles with sushi dinner too.
Frozen on the half shell mussles.(green lip)thawed.
(for the sauce)
mayo,soy,splenda,little sri hacha chili sauce.
Mix and put about 3/4 tsp on each mussle and then 1 drop sri hacha on top for garnish.
broil until bubbly and brown.