Prep: Preheat the oven to 425F and line a baking sheet with a silicone mat or parchment paper. Tear the tofu into bite-sized chunks for a more meat-like shape and texture, or cut into small cubes.
Tofu: Add the tofu to a medium bowl and add in the oil and soy sauce. Toss with a spatula until evenly coated, then sprinkle the cornstarch on top and toss again. Transfer to a baking sheet and spread out the tofu pieces so they aren’t touching. Bake on the top rack of the oven for 30 minutes, flipping the tofu halfway through.
Sauce: Whisk the water, soy sauce, mirin, sugar, and cornstarch together in a small bowl. Set aside.
Teriyaki Sauce: Warm the sesame oil in a large sauté pan over medium heat. Add the garlic and ginger and sauté for 30 to 60 seconds, until fragrant. Stir the sauce again to make sure the cornstarch is dissolved, then pour it into the pan. Bring to a simmer and cook for an additional 5 to 7 minutes, stirring occasionally, until the sauce has thickened to your liking. If the sauce gets too thick you can thin it out with additional water.
Final Touches: Turn the heat to low, then stir in the baked tofu, sesame seeds, and green onion. Taste the sauce and add more soy sauce to taste, if necessary. Divide the tofu between serving bowls and serve warm, with vegetables and rice or as desired. Leftovers will keep in the fridge for up to 5 days.
Gluten-Free: Use a gluten-free soy sauce or tamari to make this recipe gluten-free
Ginger: For a mild, more traditional teriyaki flavor, use only 1 tablespoon of fresh ginger. If you prefer a stronger and spicy ginger flavor like me, I recommend using up to 2 tablespoons!
Mirin Substitute: replace the mirin with 1 tablespoon of rice vinegar and 2 tablespoons of water. Rice vinegar is significantly less sweet, so if using, add an additional tablespoon of brown sugar to counterbalance this if needed.