Vegetarian Grilled Mushroom Burger | ElectricGrill

Ingredients

• 4 large portobello mushrooms, stems removed
• 2 tbsp olive oil
• 1 tbsp balsamic vinegar
• 1 tsp garlic powder
• 1 tsp salt
• 1/2 tsp black pepper
• 4 burger buns
• Lettuce leaves
• Sliced tomatoes
• Sliced red onion