Light Lunch: Stuffed Portobello Mushrooms

Ingredients

• 4 large Portobello mushrooms
• 4 tablespoons olive oil
• 1/8 cup butter
• 2 sprigs rosemary
• 1 large red onion
• 2 garlic cloves
• 1 2/3 cups sundried tomatoes in oil
• 2 1/4 ounces sourdough bread
• 1 tablespoon pine nuts
• 1 tablespoon dried oregano
• Generous 3/4 cup mozzarella
• Scant 1/2 cup Cheddar
• Salt and freshly ground black pepper
• salad leaves
• Balsamic dressing (optional)