Combine soda and 2 tablespoons salt; rub over surface of tongue. Scrub with a stiff brush; rinse with cold water.
Place tongue and 1 teaspoon salt in a large Dutch oven; add water to cover. Bring to a boil; reduce heat. Cover; simmer 3 hours or until tender.
Remove tongue from broth, and plunge into cold water. Reserve 1 cup broth. Remove and discard skin from tongue. Cut tongue into 1/2-inch-thick slices.
Place butter in a heavy saucepan. Cook over low heat until golden brown. Add flour; stir until smooth. Cook 1 minute, stirring constantly. Gradually add reserved 1 cup broth; cook over medium heat, stirring constantly, until thickened.
Stir in 1/4 teaspoon salt, and remaining ingredients. Add sliced tongue, and simmer, uncovered, 30 minutes. Discard bay leaves.
Place tongue on warm platter and serve with pan liquid.