Special equipment: an Instant Pot® multi-cooker and an immersion blender
Set the Instant Pot® (see Cook's Note) to normal saute. Add the oil and once shimmering, but not smoking, add the onion and cook, stirring, until translucent and soft, about 5 minutes.
Add the garlic, chili powder, cumin and oregano and cook, stirring, until fragrant, about 1 minute. Add the beans, bay leaves and 7 cups water. Follow the manufacturer's guide for locking the lid and preparing to cook. Set to pressure cook on high for 1 hour.
After the pressure cook cycle is complete, follow the manufacturer's guide for quick release and wait until the quick release cycle is complete. Careful of any remaining steam, unlock and remove the lid and remove the bay leaves. Then remove 1 cup of the beans with a slotted spoon and set aside. Use an immersion blender to blend the black beans with 1 tablespoon salt until thick and creamy. Stir in the reserved whole beans and season to taste with salt and pepper. Serve with sliced avocado, cilantro leaves, chopped scallions, lime wedges and sour cream.
Settings may vary on your Instant Pot® depending on the model. Please refer to the manufacturer's guide.