1. Cook quinoa: In a saucepan, bring water to a boil. Add quinoa, reduce heat to low, cover, and simmer for 15 minutes or until water is absorbed. Fluff with a fork.
2. Roast mushrooms: Preheat oven to 400°F (200°C). Place sliced mushrooms on a baking sheet, drizzle with olive oil, and season with salt and pepper. Roast for 20 minutes.
3. Assemble salad: In a large mixing bowl, combine cooked quinoa, roasted mushrooms, cherry tomatoes, parsley, and lemon juice. Toss well.
4. Serve: Divide the salad into bowls and serve immediately.