Add all the ingredients except the cornstarch slurry to a saucepan. Whisk together, bring to a light boil, then reduce the heat and simmer for five minutes.
Combine the cornstarch and water in a small bowl, then pour into the saucepan. Whisk and heat for another 2 - 3 minutes or until it starts to thicken. Remove from heat and let cool. Store in the fridge.
Tofu Filets
Make sure to use super firm tofu, the kind that's vacuum sealed and doesn't need pressing. Otherwise, if you are using extra firm, you should press it for at least 30 minutes.
Cut block of tofu into 4 filets. Optional but recommended, carve each rectangular filet into a more chicken breast like shape. You can also shave off the edges to make them smoother if you choose as well.
Lightly score the filets on each side, but only score them one way (as opposed to cross hatch). This will help the marinade penetrate as well as create a more "shreddy" type of texture.
Marinade for at least 30 minutes to overnight or even longer.
Get a pan up to medium high heat, add a little oil and then grill the filets for about 5 minutes per side. Once flipped, brush on some of the Teriyaki Sauce. Flip again, but only cook for a minute or so, careful not to burn the Teriyaki Sauce. Flip and brush again, and then remove from the heat and serve!
Notes
*I highly recommend using Super Firm Tofu as it doesn't need pressing. If you can only get Extra Firm, simply press it for at least 30 minutes.