After reviewing top vegetarian bistros, I’ve learned that portobello mushrooms can satisfy even hearty appetites when prepared with the right seasonings. This recipe treats large caps as “steaks,” marinating them for depth, grilling to smoky perfection, and topping with onions slowly caramelized in balsamic vinegar. The result is a bold, savory dish that stands on its own as a main course.

Ingredients

• 4 large portobello caps, stems removed

• 3 tbsp olive oil, divided

• 2 tbsp balsamic vinegar, divided

• 2 garlic cloves, minced

• Salt and pepper

• Caramelized Onions:

  • 2 large yellow onions, thinly sliced

  • 1 tbsp butter

  • 1 tbsp balsamic vinegar

Steps

1. Marinate mushrooms: Whisk 2 tbsp oil, 1 tbsp balsamic, garlic, salt, and pepper. Brush over mushrooms; let sit 20 minutes.

2. Caramelize onions: In a skillet over medium-low, melt butter and 1 tbsp oil. Add onions; cook, stirring occasionally, until golden and soft (20–25 minutes). Stir in balsamic vinegar and season.

3. Grill mushrooms: Preheat grill or grill pan to medium-high. Grill caps 4–5 minutes per side until tender and charred.

4. Assemble: Plate mushrooms and top with caramelized onions. Garnish with chopped parsley or thyme.

Professional Advice

• Slow onion cooking: Low heat maximizes sweetness—patience is key.

• Marinade absorption: Let mushrooms rest to absorb maximum flavor.

• Serving idea: Pair with mashed potatoes or a grain salad for a complete meal.

These portobello “steaks” showcase vegetarian cuisine’s potential for depth and satisfaction. The interplay of smoky grill notes and sweet onions creates a dish that appeals to all palates.