1. In a large nonstick frying pan with a lid, sauté onion in oil until beginning to brown. Add mushrooms and continue to sauté until softened.
2. Push vegetables to one side of the pan. Add chicken in a single layer and sear on both sides.
3. Add remaining ingredients to the pan and bring to a boil. Lower heat and simmer covered for 15 minutes, or until quinoa is cooked through. Serve hot.