In a small bowl take all the sauce, salt, sugar, pepper and mix very well. Keep aside.
Press the sauté button on less mode for 7 to 8 minutes on a 6 Quart Instant Pot.
Let it display hot and then add 2 tablespoons oil.
Now add the ginger, garlic and green chilies and sauté on less mode for 1 to 2 minutes.
Add the chopped scallions (spring onions) and celery.
Press sauté again and set to normal mode. Sauté onions for minute.
Add chopped mushrooms (200 to 250 grams) and ⅓ cup sliced bell pepper (capsicum).
Sauté for 2 minutes stirring often. If the onions, ginger and garlic, etc start sticking at the bottom, then change the sauté heat setting to less.
Add the prepared sauce mixture and mix very well.
Add water or vegetable stock. Mix again.
Cancel the sauté mode. Secure the instant pot with its lid and position the steam release handle to sealing. Press the pressure cook button on high pressure and set the time for 5 minutes.
Meanwhile, make a slurry or paste by mixing 2 teaspoons tapioca starch or corn starch or potato starch with 1 tablespoon water. Keep aside.
After 5 minutes, do a quick pressure release and then open the lid.
Stir the prepared slurry and add it to the mushrooms. Mix again very well.
Press the sauté button again on normal mode for 1 to 2 minutes.
Let the sauce simmer for 1 to 2 minutes or more till the sauce or gravy thickens and the rawness of the starch is not felt. If gravy becomes too thick add some hot water.
Once the sauce gets thickened, press cancel button. Sprinkle some scallion greens or spring onion greens. Stir and mix.
Check the taste and add bragg's liquid amino or soy sauce, sugar, salt or crushed black pepper more if required.
Serve instant pot chilli mushroom gravy hot with bread rolls, fried rice, noodles or fettuccine pasta. garnish with some finely chopped scallion greens while serving.
Notes
Green chilies, garlic, ginger, red chili paste, black pepper powder, salt and sugar can be adjusted to suit one's taste.
Take care when sauteing the garlic, ginger, green chillies so that they do not get browned or burn.
Add more water or veg stock for a slight thin soupy sauce.
If using sweet rice wine or mirin instead of vinegar, then reduce the sugar or skip it.
You can even add both salt and sugar towards the end, once the instant pot mushroom chilli is done.
Add less salt as the sauces already have salt in them.