Place the chiles in a heat-safe blender (or heat-safe bowl if your blender pitcher is plastic), and cover with the boiling water. Set aside and let cool completely. Once cool, add onion, garlic, and oregano to the blender and blend until smooth.
Season the pork with 2 teaspoons of salt and 1 teaspoon ground black pepper. Set the Instant Pot to sauté. When hot, add the oil, and carefully brown the pork pieces (8–12 minutes, about 4 minutes per side). Remove the pork with tongs and set aside.
Turn off the sauté function. The Instant Pot will remain hot. Carefully add the chile puree—watch for splattering—and use a wooden spoon to scrape up any brown porky bits from the bottom of the pan. Cook, stirring, for a couple of minutes.
Use the chicken stock to rinse out the blender and add to the Instant Pot along with the pork, bay leaf, a large pinch of salt, and a good amount of black pepper. Stir to combine.
Set Instant Pot to cook for 20 minutes at high pressure. Release the pressure manually.
Carefully remove the bay leaf and add the hominy. Stir. Set the Instant Pot to cook at high pressure for 5 minutes. Release the pressure manually. Serve with any/all of the garnishes you please.