Mix the ingredients: in a small saucepan, mix the soy sauce, mirin, sake, and brown sugar or maple syrup. If using garlic and ginger, add them as well.

Cooking: bring the mixture to a boil over medium heat, then reduce to simmer.

Reduction: allow the sauce to simmer for about 10-15 minutes, or until it slightly reduces and becomes a bit syrupy.

Straining: if you added garlic and ginger, you may strain the sauce through a fine sieve to remove the pieces. But this is optional.

Reserve: let the sauce cool before using.

Prepare the tofu: drain and press the tofu to remove excess water. Cut it into approximately 2 cm cubes.

Marinating: place the tofu cubes in a bowl and pour half of the homemade teriyaki sauce over them. Mix well to coat the tofu. Allow it to marinate for at least 30 minutes.

Note: while the tofu is marinating, you have about 30 minutes of free time. This is the ideal moment to prepare a wakame soup to accompany your dish. The link to the recipe can be found in the text above.

Prepare the vegetables: in the meantime, wash and cut the shiitake mushrooms, carrots, onion, and bell pepper.

Cook the vegetables: in a large skillet or wok, heat a tablespoon of sesame oil over medium-high heat. Add the onion, carrots, bell peppers, and shiitake mushrooms. Sauté until they are tender but still crunchy. Reserve the vegetables in a bowl.

Cook the tofu: in the same pan, add the remaining tablespoon of sesame oil. Add the tofu cubes and brown them on all sides.

Assemble: once the tofu is browned, return the vegetables to the pan. Pour the remaining homemade teriyaki sauce and mix well to coat all ingredients.

Finish: sprinkle with sesame seeds and sliced green onion if you wish.

Serve: serve hot with rice or noodles.