Sort and rinse the peas in a colander and place them in a large pot. Cover the peas with water - about 2 inches above the peas. Add the salt and cook covered on low heat for about 3 hours, stirring occasionally. If they get too dry, bring a small amout of water to a boil and add it to the peas until they are desired consistancy. Add the sausage, onion, and tomatoes and simmer for about 45 minutes. Add rice, oregano, and black pepper and add more salt, if needed.