Grease a 3-quart baking dish. In a bowl, combine tomatoes, sugar, paste, mustard, soda, and salt. Place bread cubes in the baking dish; drizzle with melted butter. Pour tomato mixture over bread. Refrigerate up to 4 hours, if desired.
Bake at 375° for 35 to 40 minutes, or until hot and bubbly. Garnish with fresh parsley sprigs, if desired.