- 4 large sweet onions such as Vidalia, Walla Walla, or Oso Sweet (3 to 4 lb total)
- 1 1/2 cups tomato juice (12 fluid ounces)
- 1 1/2 cups water
- 2 tablespoons unsalted butter
- 2 tablespoons molasses (regular or robust; not blackstrap)
- 1/2 teaspoon salt, or to taste
- 8 bacon slices (1/2 pound), halved crosswise
Put oven rack in middle position and preheat oven to 400°F.
Peel and trim onions, keeping root ends intact, then halve each lengthwise. Arrange, cut sides up, in 1 layer in a 13- by 9- by 2-inch glass baking dish or other 2 1/2-quart shallow baking dish.
Bring tomato juice, water, butter, molasses, and salt to a boil in a 2-quart heavy saucepan, stirring occasionally, then pour over onions. Bake onions, uncovered, basting with juices every 30 minutes, until tender, about 2 hours.
Lay 2 pieces of bacon side by side over each onion half and continue to bake onions, basting once with juices halfway through baking, until onions are very tender, bacon is browned, and juices are thickened, about 1 hour more.
Cooks’ note: Onions can be baked 1 day ahead and chilled, covered. Reheat, covered with foil, in a preheated 350°F oven 20 to 30 minutes.