- Nonstick vegetable oil spray
- 6 medium onions (about 2 1/2 pounds), peeled, each cut vertically through root end into 12 to 14 wedges
- 6 tablespoons (3/4 stick) butter
- 2 cups canned low-salt chicken broth
- 3 tablespoons sugar
- 2 tablespoons red wine vinegar
- 3 pounds slender green beans, ends trimmed
- Preheat oven to 450°F. Spray 2 heavy large baking sheets with vegetable oil spray. Arrange onions in single layer on prepared sheets.
- Dot onions with 4 tablespoons butter, dividing equally. Season with salt and pepper. Bake until onions are dark brown on bottom, about 35 minutes.
- Meanwhile, boil broth in heavy large skillet over high heat until reduced to 1/2 cup, about 6 minutes. Add sugar and vinegar and whisk until sugar dissolves and mixture comes to boil.
- Add onions to sauce; reduce heat to medium-low. Simmer until liquid is slightly reduced, about 5 minutes. Season with salt and pepper. (Can be prepared 1 day ahead. Cover and refrigerate. Rewarm over low heat before continuing.)
- Cook green beans in large pot of boiling salted water until crisp-tender, about 5 minutes. Drain well. Return beans to same pot. Add remaining 2 tablespoons butter and toss to coat. Mound beans in large shallow bowl. Top with onion mixture and serve.