Toast the peptitas over medium heat in a small frying pan. Add them to a blender and blend until ground. Set the blender aside with the ground pepitas, you will add more to it later.
Add the chicken, tomatillos, jalapeno, poblano, onion, garlic, Mexican oregano, chicken stock and salt to the Instant Pot. Cover the Instant Pot and cook on high pressure for 15 minutes.
Release the steam from the Instant Pot. Remove the chicken from the mixture and place on a cutting board to cool. Place a strainer over a large bowl. Pour the rest of the contents from the pot through the strainer to separate the solid ingredients from the liquid. Place the liquid back in the Instant Pot and place the solid ingredients in the blender with the ground pepitas. Add the cilantro and blend until smooth and add to the liquid in the Instant Pot.
Using 2 forks shred the chicken and add it to the Instant Pot. Add the hominy and stir until blended. Place the Instant Pot on the saute function and heat until the soup is heated through. Garnish with the tortillas, avocado, onions, cilantro and a big squeeze of lime juice. Serve hot and enjoy!