Directions

1. Heat broiler; set rack 4 inches from heat. In a small bowl, whisk together vinegar, oil, 1 teaspoon salt, and 1/4 teaspoon pepper.
2. On a large rimmed broiler-proof baking sheet, toss mushrooms with half the dressing (reserve the rest); broil, tossing occasionally, until most of the liquid has evaporated and mushrooms are tender, 20 to 25 minutes.
3. Meanwhile, in a small saucepan, combine quinoa, 3 cups water, and 1 1/2 teaspoons salt. Bring to a boil; reduce heat to medium. Cover, and simmer until liquid has been absorbed, 15 to 20 minutes.
4. Place spinach in a large bowl; add hot mushrooms, quinoa, and reserved dressing. Toss to combine (spinach will wilt slightly). Top with crumbled feta, and serve immediately.