Here is the recipe I found at Meals Matter:
Green Beans and Pan-Roasted Red Onions
5 cups water
1 lb green beans, trimmed
1 Tbsp olive oil
3 red onions, each cut into 8 wedges (I used 3 very small onions)
1/2 cup chicken broth
1 Tbsp balsamic vinegar
2 tsp brown sugar
1/4 tsp salt
1/4 tsp black pepper
Bring water to a boil in a large saucepan; add beans. Cook 6 minutes or until crisp-tender. Drain; keep warm.
Heat oil in a large nonstick skillet over medium-high heat. Add onions; saute 8 minutes or until browned. Add broth; cook 3 minutes, stirring occasionally. Stir in vinegar and remaining ingredients. Stir in beans; cover and cook 2 minutes.