Ingredients
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
Preparation
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.
