Chop the onion and bell peppers. Set the Instant Pot into a Saute mode and add the olive oil, then bring in the chorizo sausage and break it up into chunks with a spatula, brown until cooked.
Add the chopped onions and bell peppers and cook until slightly softened for about 5 minutes. If they start to burn, deglaze with 1/4 cup of the chicken stock. Then add the minced garlic and all spices listed, stir to coat.
Pour in the canned tomatoes together with the juices, drained black beans, corn (can be still frozen), 2 whole chicken breasts, chicken stock and 1 tsp of salt.
Cook on manual at hight pressure for 10 min. Once the time is up, allow for a natural release, which will take between 15-20 minutes. Open the Instant Pot and take out the chicken breasts, shred them with two forks and return to the pot. Stir to combine.
While the soup is cooking, preheat the oven to 180C/350F, cut the corn tortillas in quarters and toss with the olive oil. Arrange for a baking sheet in a single layer and bake for 10 minutes till crispy. Once done, remove from the baking sheet immediately or they will continue cooking and will burn.
Serve the soup topped with sliced green onions, sour cream, chopped cilantro (coriander), crispy tortilla and and a scoop of cooked rice if desired.