Make seasoning mix: Grind bay leaves and mix with remaining spices and herbs.
In a heavy 7- to 8-quart pot or kettle melt butter over low heat. Add onions, green pepper, celery, garlic, parsley, Tasso and pork and brown over low heat, stirring constantly, 15 minutes. Add sausage and seasoning mix, mix thoroughly and continue cooking, stirring frequently, for 20 minutes. Add rice, raise heat to medium and cook 5 minutes, or until rice is lightly browned, stirring and scraping sides and bottom of pot. Add tomatoes, stock and oysters and mix gently. Raise heat to high, bring to a boil and cook, uncovered, 5 minutes. Cover pot, reduce heat to low and cook 40 minutes, stirring gently every 5 to 10 minutes. If too dry, add 1/4 to 1/2 cup water after about 30 minutes. Uncover pot, raise heat to medium and allow rice to dry out, about 10 minutes without stirring. Stir very gently, so as not to break up oysters and serve immediately.