Heat remaining dressing in skillet on medium heat. Add mushrooms and onions; cook 5 min., stirring occasionally. Stir in garlic; cook and stir 2 min. Add quinoa and 1 cup chicken broth; cook 3 min. or until broth is absorbed, stirring constantly. Stir in remaining broth; bring to boil. Cover; simmer on medium-low heat 15 min. or until quinoa is tender.