Place the chopped onion in the pressure cooker and cook with a little water until translucent (Saute feature).
While the onion is cooking, blend the cooked beans with the salsa until smooth and creamy. Set aside.
When the onion is soft and translucent, add all of the rest of the ingredients into the pot and stir well to combine.
Cook on High Pressure for 5 minutes. Click cancel after the countdown and let the pressure cooker release steam naturally. If using, add the baby spinach now, sitr it in, close the lid, and let it wilt before serving.
Serve hot with diced avocado and a few crushed tortilla chips.