Set your Instant Pot to sauté. Add 3-4 tablespoons of water, with the onion, carrots, and celery, and sauté until softened, approx. 5 minutes. (Add more water if needed to prevent sticking.)
Add all the remaining ingredients, except the spinach, and give it a stir. Lock your lid in place, ensuring the valve is set to the sealing position. Then set to high pressure for 2 minutes. (It will take approx. 15 minutes to reach pressure.) Once complete, quick release, remove the lid and stir in the spinach until wilted.
Stove Top Directions
In a large soup pot, add 3-4 tablespoons of water, with the onion, carrots, and celery, and sauté over medium heat until softened, approx. 5 minutes. (Add more water as needed to prevent sticking.)
Then add all the remaining ingredients, except the spinach, cover your pot with a lid, and bring to a low boil. Then simmer the soup for 12-15 minutes, until the quinoa is cooked and the soup has thickened. Turn off the heat, and stir in the spinach until wilted.
Notes
Dice the onion, carrots, and celery into small pieces, but keep the zucchini pieces larger so they don't overcook and get too soft.
If using the Instant Pot method, make sure the valve on your lid is in the sealing position, or it will not reach pressure. When the timer completes, quick release immediately to prevent overcooking.
If using the stovetop method, keep your pot or saucepan covered with a lid while cooking to prevent the liquids from evaporating too much and the soup from getting too thick.
As the soup cools, the quinoa will absorb more broth. Add a little extra broth, as needed, if the soup gets thicker than you'd like.
Leftovers keep refrigerated for 3-4 days or freeze airtight for up to 3 months. Make sure to cool the soup before freezing and leave some room for expansion.