- 2 tablespoons extra-virgin olive oil
- 1 large red onion, halved and thinly sliced
- Salt and pepper
- 1 rosemary sprig
- 1 tablespoon balsamic vinegar
- 2 teaspoons soy sauce
- In a large skillet, heat the olive oil. Add the onions, season lightly with salt and pepper and cook over moderate heat until they start to soften, about 5 minutes. Add the rosemary and continue cooking the onions until very soft and just starting to brown, about 10 minutes longer.
- Add the balsamic vinegar and soy sauce and cook just until the liquid is mostly evaporated, about 1 minute. Remove the rosemary sprig and serve.