½ cup (125 ml) olive oil
100 ml balsamic vinegar
4 thick slices onion
1 teaspoon crushed garlic
½ teaspoon dried basil
4 portobello mushroom caps
1 tablespoon honey
4 bread rolls or hamburger buns, split
4 lettuce leaves
4 slices tomato
125 g mozzarella, thickly sliced
- In a clean plastic bag, combine 3 tablespoons of the oil and 2 tablespoons of the vinegar. Add the onion slices and turn to coat. Seal the bag and set aside to marinate for 30 minutes.
- Meanwhile, in a small bowl, combine the garlic, basil and remaining oil. Brush over both sides of the mushroom caps and set aside.
- In a small saucepan, bring the honey and remaining vinegar to the boil and cook for 5 minutes, or until thickened. Set aside.
- Preheat a barbecue hotplate or grill rack to medium heat. Drain the onions and discard the marinade. Cook the onions and mushrooms on the hotplate or grill rack over direct heat for 10-12 minutes, turning regularly. Place on rolls or buns with lettuce, tomato and mozzarella. Drizzle with the balsamic-honey sauce.