In a large skillet with a cover, heat the olive oil and add the onion slices. Sauté until just soft, about 5 minutes. Add the Roasted Red Pepper Sauce and bring to a simmer. Stir in the green beans, covering them with the sauce. Put the lid on the pan and cook until the beans are tender.
Serve hot or cold. Garnish by sprinkling with chopped fresh rosemary. Makes 6 servings.