In a large, heavy stockpot, heat the oil over medium-high heat. Add the ham hocks, onions, celery, bell pepper, red pepper flakes, oregano, thyme and bay leaves, and saute until soft, about 5 minutes. Add the garlic, and saute for 1 minute. Add the stock and bring to a boil over high heat. Reduce the heat to medium-low and simmer covered for 1 1/2 hours, stirring occasionally.
Add the navy beans and stir. Continue simmering over medium-low heat for 45 minutes to one hour, or until the beans are almost cooked and ham hocks are very tender. Season with salt and continue cooking 15 to 30 minutes, until beans are done and ham hocks are beginning to fall apart.
Remove from the heat. Serve the ham hocks with the beans at the table, sprinkled with parsley and green onions, or cut the meat from the bones in the kitchen before serving, return the meat to the pot and serve with the beans at the table.