Preheat the oven to 400 degrees F. Season the pork shoulder with salt and pepper. Place the roast, fat side up, on a baking sheet, lined with parchment paper. Place 1 cup of water in the roasting pan. Cook the pork for 1 hour. Reduce the heat to 300 degrees F. Continue to cook for 6 hours. Remove from the oven and cool completely. Using a fork, shred the meat. Set the pork aside. In a Dutch oven, over medium heat, add the oil. When the oil is hot, add the Tasso. Render the ham for 3 minutes. Add the trinity (the onions, peppers and celery). Season with salt and cayenne. Saute for 4 minutes. Stir in the garlic, bay leaves and tomatoes. Continue to cook for 3 minutes. Stir in the rice and water. Bring the liquid to a boil, reduce the heat to medium-low and simmer for 25 to 30 minutes, or until the rice is tender. Remove from the heat and stir in the reserved pork and green onions. Reseason with salt and pepper. Serve hot with crusty French bread.