Drain the tuna.
Remove stem ends and quarter the shiitake mushrooms.
Boil the spaghetti according to the directions on the package.
- Place the olive oil and garlic into a frypan and sauté over medium flame, when the mixture becomes fragrant, add in the onions and shiitake and continue to cook over strong flame.
- Add and mix in the cut tomatoes, allow to boil and then add tuna and spaghetti, sauté together adding soy sauce and black pepper to season to taste.