Quick soak the beans by placing them in the pressure cooker with 4 cups water. Lock the lid in place, bring to HIGH pressure and cook for 2 minutes. Release the pressure, drain and rinse the beans in cold water.
Return the beans to the pressure cooker along with the 1 tablespoon oil (to reduce foaming), season with salt, and cover with 4 cups water. Lock the lid in place, bring to HIGH pressure and cook for 7 minutes. Release the pressure, drain, rinse the beans, and set aside.
In the pressure cooker, sauté the diced bacon over medium heat. Remove the cooked bacon with a slotted spoon and set it aside. Remove all but 2 tablespoons of the bacon fat and use this to sauté the onion, garlic, and chilies.
When the onion is transparent, return the beans and reserved bacon to the cooker. Season with salt and pepper. Simmer for 5 minutes to allow the seasonings and blend before serving.