Green Beans with Balsamic-Shallot Butter

Green beans are starting to wrestle for space in our teeming farmer's markets. I've just blanched 20 pounds of them for freezer storage and have held some back for tonight's dinner. I like the palate cleansing attributes of this recipe and make it several times during harvest season. It's not my favorite recipe for beans but it's perfect for summer's busy kitchen. The original recipe, which appeared in Bon Appetit magazine a decade ago, was made with dark balsamic vinegar. The beans had wonderful flavor but their color was really dreadful. I've since substituted white balsamic vinegar and am much happier with their appearance. Save for a final toss and stir-fry, done to reheat rather than cook, these beans can be made ahead of time. They are a real hostess helper. Here's the recipe.

Green Beans with Balsamic-Shallot Butter

Ingredients:
1/2 cup white balsamic vinegar
2 large shallots, finely chopped (1/2 cup chopped red onions may be substituted)
4 tablespoons (1/2 stick) butter, room temperature
Optional garnish: Coarse sea salt
2 pounds green beans, trimmed

Directions:
1) Combine vinegar and shallots in heavy small saucepan. Boil over medium heat until most vinegar is absorbed (about 1 tablespoon liquid should remain in pan), stirring frequently, about 6 minutes. Transfer mixture to small bowl; cool completely. Add butter; mix with fork until blended.
2) Cook beans in large pot of boiling salted water until crisp-tender, about 6 minutes. Drain. Refresh under cold water; drain. Pat dry with paper towels. Balsamic-shallot butter and beans can be made 1 day ahead. Cover separately; chill.
3) Combine beans and balsamic-shallot butter in large nonstick skillet. Toss over medium heat until beans are heated through, about 5 minutes. Season to taste with salt and pepper and serve. Yield: 8 servings.