The night before, place the dried pinto beans in a large bowl and cover with plenty of water. Soak for 8–12 hours or overnight, then drain and rinse well.
Place the soaked beans in your Instant Pot and cover with 1–2 inches of water or a mixture of broth and water. Secure the lid, set the valve to Sealing, and cook on High Pressure for 20 minutes. Allow 15–20 minutes of natural pressure release, then carefully release any remaining pressure.
Check that the beans are tender but not falling apart. Use a ladle to remove some of the cooking liquid, leaving enough to cover the beans by about 1/2 inch.
Stir in the tomato paste, soy sauce, molasses, onion powder, garlic powder, smoked paprika, salt, and black pepper. Select Sauté and simmer for 10–20 minutes, stirring occasionally.
In a small bowl, mix the flour with a little cooking liquid until smooth. Stir the paste into the beans and cook for about 1 minute, stirring constantly, until the sauce thickens.
Turn off the Sauté setting and stir in the butter until melted. Serve hot with buttered sourdough bread.