In a bowl, combine all the sauce ingredients and stir to evenly mix everything and attain a slightly thick sauce that looks like this.
In a large pan or wok, heat about 2 tablespoons of vegetable oil and sauté garlic, followed by onion. Add the carrot when the onion is translucent.
Continue cooking then add the celery when the carrot is cooked through, followed by the mushroom and green onions.
When all veggies are already cooked, pour the sauce mixture. Continue cooking while stirring to have a smooth consistency. Cook until the sauce thickens. Transfer the sauce to a bowl and set aside.
In the meantime cook the tofu. If you have sizzling plate, heat the plate in the stove until very hot that droplets of water will disappear in an instant.
Add some oil and cook the tofu by slightly browning, first on one side then on the underside. Then pour the sauce to create that wonderful sizzling-smoking effect.