In a small bowl make the seasoning mix. Set aside.

Combine oysters and water; stir and refrigerate for at least one hour. Strain and reserve the oysters and oyster water separately in refrigerator until ready to use.

Preheat oven to 350ºF.
Melt 4 tablespoons margarine in a large skillet, preferably cast iron, over high heat. Add 3/4 cup onions, 1/2 cup celery and 1/2 cup bell peppers. Saute over high heat until onions are dark brown but not burned, about 8 minutes, stirring frequently.

When onions are browned add 2 teaspoons of the seasoning mix and the garlic to the skillet. Reduce heat to medium and continue cooking for 5 minutes, stirring occasionally. Add the remaining 3/4 cup onions, 1/2 cup celery and 1/2 cup bell peppers, 4 tablespoons margarine and bay leaves. Stir until the margarine is melted and cook for 10 minutes, stirring occasionally. Stir in the reserved oyster water and cook over high heat for 10 minutes, stirring occasionally.
Stir in the remaining seasoning mix and enough bread crumbs to make a moist but not runny dressing. Remove from heat. Stir in the drained oysters.

Spoon dressing into an ungreased 8 x 8 x 2-inch baking dish and bake uncovered for 30 minutes.
Remove from oven and discard bay leaves. Swirl in the butter and green onions.