Heat coconut oil or olive oil in Instant Pot on sauté.
Add cut carrot, celery, onion and eggplant pieces. Sauté for a few minutes. Then add water and rest of ingredients.
Put pressure lid on IP and select stock or soup function. On my machine, 15 minutes appears, which is the length of time it takes to cook under pressure. This can also be made in a traditional pot on the stove. Put sautéed vegetables and rest of ingredients in a large stock pot on high on the stove. Bring to a boil, then reduce to a simmer. Let the mixture simmer for about an hour with the lid partly off so it doesn't boil over. When finished, allow a natural release of the IP pressure. Open lid (there will be steam, so don't put your face over the pot). Pour mixture through a sieve into a large container.
Once cooled, stock can be kept in a quart jar in the refrigerator for use in the next couple of days. I often put a few cups in a plastic back and freeze it for later use.