So long as it isn’t smothered in sauces and deep fried this should be do- able (a little soy sauce is fine by the way). A serve size of brown rice is half a cup so this may be equivalent to 1, or two small sushi roll slices. It would have to be eaten as part of a meal (lunch or dinner) and you would need to include with it 2 cups of non starchy vegetables and 1 serve of protein (there may be a small amount of these included in the sushi but obviously not enough).
If you were wanting one of the more indulgent looking sushi (with all the trimmings, etc) then it would be best to save this for your free meal.
BT Nutritionist 🙂