In sauté pan over medium heat, add peanut oil. Add mushrooms. Season with salt and pepper. Cook half way. Place in bowl. Toss with remaining ingredients. Chill.
Place parsnips in saucepan. Cover with cool water. Simmer 50 minutes until water is 90 percent absorbed. Add 4 tablespoons butter. Mash. Season with salt and pepper.
Serve the mushrooms atop mashed parsnips. I recommend this with pan-seared Mahi Mahi!