- 4 tsp olive oil
- 1 medium uncooked onion(s), finely chopped
Bring 3 quarts of water to a boil in a large saucepan; set over high heat.
Meanwhile, heat the oil in a large nonstick skillet over medium-high heat. Add the onion and garlic; cook, stirring frequently, until light golden brown, about 4 minutes. Add the chicken and cook, breaking it apart with a wooden spoon until browned, about 3 minutes. Add the mushrooms, salt, and pepper; cook, stirring occasionally, about 2 minutes. Add the tomato sauce and vinegar; bring to a simmer.
Meanwhile, add the pasta to the boiling water and cook until al dente, about 2 minutes. Drain, reserving 1⁄2 cup of the pasta cooking water. Mix the pasta with the mushroom mixture, adding the reserved water to moisten. Yields 1 1/2 cups per serving.