Frijoles (Peruanos) de la Olla

Remove any pebbles or debris from beans. Transfer to a colander and rinse. Soak beans at least 3 hours to overnight in 3 cups water. Drain. Fill a large, heavy bottom pot with water. Add beans, making sure the water is at least 1-inch over the beans. Add onion, garlic and olive oil. Heat over low medium heat. Cover a steam vent lid. If your lid does not have a steam vent, cover with the lid slightly off to let steam escape. Simmer for 90 minutes, checking for water level to be 1-inch over beans at all times. Add boiling water when water level decreases. Add salt during the last 10 minutes of cooking. (Taste test the broth (not the beans) to check if more salt is needed). Remove from heat. Let cool slightly for 10 minutes. Serve with pico de gallo and a slice of queso fresco.