Preheat the oven to 400 degrees.

Place the sliced mushrooms, balsamic vinegar, olive oil, minced garlic, soy sauce, thyme and salt and pepper to taste in a large mixing bowl, and stir to combine well.

Pour the mushrooms into a well greased roasting pan or casserole dish, and bake for 20 minutes, or until the mushrooms are tender to your liking.

Garnish with freshly chopped parsley before serving.