This dish is great served at room temperature, so it's a real boon at Thanksgiving. You can trim the green beans and caramelize the onions a day in advance.
Source: Everyday Food, November 2011
Prep Time 40 minutes
Total Time 50 minutes
1 tablespoon plus 1 teaspoon extra-virgin olive oil
2 large sweet onions, such as Vidalia (about 1 1/4 pounds), thinly sliced
Coarse salt and ground pepper
2 pounds green beans, trimmed
4 teaspoons chopped fresh tarragon leaves
In a large nonstick skillet, heat 1 tablespoon oil over medium-high. Add onions and season with salt and pepper. Cook, stirring often, until softened and just beginning to brown, 10 minutes. Reduce heat to medium; cook, stirring occasionally, until onions are deep golden brown and very soft, 30 minutes. (Refrigerate in an airtight container, up to 1 day. Bring to room temperature before using.)
Meanwhile, in a large pot of boiling salted water, cook green beans until crisp-tender and bright green, about 6 minutes. Drain and toss with tarragon and 1 teaspoon oil; season with salt and pepper. Transfer beans to a platter and top with onions.
Cooking onions until they are golden brown, or caramelized, both deepens and amplifies their flavor. They're delicious on green beans, but also on pizza, baked potatoes, or grilled cheese sandwiches. You may want to make a double batch, in fact, since they're an easy way to dress up any meal.