Bring water to boil
Meanwhile, hea tthe 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 occasinally, about 2 minutes. Add the tomato sauce and vinegar, bring to a simmer.
Meanwhile, add the pasta to the boiling water and cook unti al dente. Drain reserving 1/2 cup of hte cooking water. Mix the pasta with the mushroom mixture, adding the reserved water to moisten.
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