1. Preheat oven to 375 degrees Fahreneheit. Generously oil a large cookie sheet. Combine the wheat gluten and nutritional yeast. Whisk together the water, liquid smoke and tahini paste separately. Pour the wet ingredients into the dry and mix together with your hands until combined. It will be wet.
2. Knead for a minute or so. Flatten out the dough as much as possible and tear into bite-sized strips. Place on the cookie sheet and bake 10 minutes, flipping halfway through. Set aside. My seitan was in the fridge for a couple of days and it was wetter from condensation when I stir fried it. If you go straight from oven to stir fry, yours may caramelize better but may also stick to the pan more. Don't be afraid of the oil!
3. Combine the mirin, soy sauce and sugar. Stir in the ginger. Combine the corn starch and water to make the thickener. Heat a wok between medium and medium-high heat. Drizzle with oil and add the baked seitan. Stir frequently, browning the seitan, 3-4 minutes.
4. Remove from the wok. Drizzle some more oil and add the garlic and red pepper flakes, cooking 30 seconds. Remove and add to the seitan. Add the carrots and chard stems to the wok. Slowly add the chard leaves, wilting them in. Pour in the mirin and soy sauce mixture. You can add some water at this point if you would like to make more sauce.
5. Add the seitan and garlic back in and pour in the corn starch and water mixture. Remove from the heat and stir to combine. The sauce will thicken. Serve!
Source of recipe: This is my recipe. I make teriyaki stir fry just about every week to finish off the lingering veggies in the fridge.