Place the mushrooms in a large bowl.
In a small bowl whisk together the olive oil, garlic, vinegar, Dijon, ¼ tsp salt, and ⅛ tsp black pepper until well combined.
Drizzle the dressing over the mushrooms and toss to coat.
Cover the bowl and set aside to allow mushrooms to marinate for about 20 minutes.
Taste and season with additional salt & pepper if needed.
