1. Marinate the Tofu overnight in the Teriyaki sauce (make sure you leave it in refrigerator).
2. Next day drain the Tofu and reserve the Teriyaki sauce if any left. Mix the cornstarch with the water and put it aside. You will be doing some high heat sauteing so keep all the ingredients chopped and ready.
3. Heat the sesame oil in a wok or stir-fry pan and stir fry the Tofu for about 7-8 minutes. Heat should be between high and medium high. Now add the onions, followed by green peppers and stir fry for about 4 minutes. Once the onion and peppers get little sweat, add the salt, pepper, green chili sauce, soy sauce and stir. Now add the cornstarch mixed with water and give it a good stir.
4. Add the reserved Teriyaki sauce and turn the heat off and add vinegar and serve hot.
5. Make sure you make this dish just 15 minutes before you plan to serve to retain the freshness of the dish.