2 lbs green beans, ends trimmed
2 Tbsp. coarse-grain Dijon mustard
3 Tbsp. balsamic vinegar
1 1/2 Tbsp. maple syrup
2 tsp. extra-virgin olive oil
2 Tbsp. chopped green onion (including green top)
Salt and fresh-ground pepper
In a large saucepan, bring 2 quarts water to a boil over high heat. Add beans and cook, uncovered, until tender-crisp, 5 to 8 minutes; drain and pour into a bowl. Meanwhile, mix mustard with vinegar, maple syrup, and oil. Pour over hot beans and mix to coat well; sprinkle with onion. Season to taste with salt and pepper.