Marinate the Portobello Mushrooms:
In a bowl, whisk together balsamic vinegar, olive oil, minced garlic, dried thyme, smoked paprika, salt, and black pepper.
Place the cleaned portobello mushrooms in a shallow dish and pour the marinade over them. Make sure both sides of the mushrooms are well coated.
Let the mushrooms marinate for at least 30 minutes, flipping them occasionally to ensure even flavor absorption.
Prepare the Chimichurri Sauce:
In a separate bowl, combine the finely chopped parsley, cilantro, minced garlic, red wine vinegar, extra virgin olive oil, red pepper flakes, salt, and black pepper.
Stir well to combine all the ingredients. Taste and adjust the seasoning if needed. Set the sauce aside to let the flavors meld.
Grill the Portobello Mushrooms:
Preheat your grill to medium-high heat. You can also use a grill pan if you don't have an outdoor grill.
Place the marinated portobello mushrooms on the grill, gill-side down, and grill for about 4-5 minutes on each side or until they are tender and have grill marks.
During grilling, you can brush the mushrooms with any remaining marinade to keep them moist and flavorful.
Serve with Chimichurri Sauce:
Once the portobello mushrooms are grilled to perfection, transfer them to a serving platter.
Spoon a generous amount of chimichurri sauce over each mushroom.
Garnish with additional fresh herbs if desired.
Serve immediately while the mushrooms are hot and the sauce is fresh.