Cook rice in rice cooker

Mix tuna with pepper and mayonnaise

Cut avocado and mushroom into thin slices

Stir fry mushroom slightly

Mould cooked rice into patty shape

Apply teriyaki sauce on rice patty and fry in pan until it slightly hardens

Place tuna, avocado, mushroom in between 2 rice patties

Wrap the burger with seaweed and you are good to go!