- 2 pounds green beans, trimmed
- 3/4 cup apple cider vinegar
- 3/4 cup red wine vinegar
- 1/4 cup (packed) golden brown sugar
- 5 fresh thyme sprigs
- 4 whole cloves
- 1 small bay leaf
- 1 teaspoon salt
- 2 large onions, thinly sliced
- 3 tablespoons olive oil
- 1/4 cup pure maple syrup
- 1 teaspoon chopped fresh thyme
- Fill large bowl with ice and cold water. Cook beans in large pot of generously salted boiling water just until crisp-tender, 5 to 6 minutes. Drain. Place beans in bowl of ice water until cool. Drain well, then pat dry with kitchen towels. DO AHEAD: Can be made 1 day ahead. Wrap beans in several layers of paper towels; enclose in large resealable plastic bag and chill. Bring to room temperature before using.
- Combine 2 cups water, cider vinegar, and next 6 ingredients in large saucepan. Bring to boil, stirring until sugar dissolves. Add onions; bring to boil. Reduce heat and simmer until onions are wilted, about 4 minutes. Remove from heat. Cool uncovered to room temperature. DO AHEAD: Can be made 1 day ahead. Cover and chill onion mixture. Before using, drain liquid; discard thyme, cloves, and bay leaf and bring to room temperature.
- Whisk oil, syrup, and chopped thyme in large bowl. Season with salt and pepper. Add green beans and drained onions; toss to coat. Transfer salad to platter and serve.