Preheat your oven to 400°F (200°C).
In a large mixing bowl, combine the balsamic vinegar, soy sauce, olive oil, minced garlic, dried thyme, black pepper, and salt. Whisk until well blended.
Add the cleaned mushrooms to the bowl and toss them in the marinade until they are fully coated.
Spread the marinated mushrooms in a single layer on a baking sheet lined with parchment paper.
Roast in the preheated oven for 20-25 minutes, or until the mushrooms are tender and caramelized, stirring halfway through for even cooking.
Remove from the oven and let cool slightly. Garnish with fresh chopped parsley before serving.