Peel onions and cut an "X" in stem ends to prevent them from splitting. Melt butter in a 10-inch skillet over medium heat; add onions and brown lightly.
Stir in beef broth, tomato sauce, vinegar, raisins, sugar, thyme, salt, and bay leaf and bring to a boil; cover, reduce heat to low, and simmer 40 to 45 minutes or until onions are tender. Remove bay leaf.
Combine water and cornstarch in a small cup and stir into onion mixture. Add TABASCO® Sauce. Cook and stir until mixture boils and thickens.
Makes 6 servings.