Select the Sauté setting on the Instant Pot, add the oil, and heat for 1 minute. Add the onion, garlic, carrots, celery, and salt. Sauté for about 10 minutes, until the vegetables give up some of their liquid and begin to brown just a bit. Stir in the tomato paste and nutritional yeast, then add 1 cup of the water and use a wooden spoon to nudge loose any browned bits from the bottom of the pot. Add the peppercorns, bay leaves, parsley, and remaining 7 cups water, making sure not to fill the pot more than two-thirds full.