Preheat your grill to medium-high heat. If using a grill pan, preheat it on the stovetop.
In a mixing bowl, whisk together the olive oil, minced garlic, balsamic vinegar, oregano, thyme, salt, and black pepper to create the marinade.
Clean the mushrooms with a damp paper towel to remove any dirt. Remove the stems and place the mushrooms in the marinade, ensuring they are evenly coated. Allow them to marinate for 10 minutes for enhanced flavor.
Place the marinated mushrooms on the grill, gill side down. Cook for about 6-8 minutes, then flip them carefully with tongs.
Continue grilling for another 6-8 minutes or until the mushrooms are tender and have nice grill marks.
Remove the mushrooms from the grill and let them rest for a couple of minutes before serving.
Serve warm as a side dish or as a topping for salads, burgers, or sandwiches.