I usually serve 2 smaller mushrooms topped with the cheese and tomato confit, but if they're very large, one will be enough. Technically this is not a burger, but more like a steak.
3 tablespoons olive oil
2 tablespoons balsamic vinegar
2 cloves garlic, finely chopped
2 shallots, finely chopped
1 tablespoon Dijon mustard
8 portobello mushrooms
Salt and freshly ground pepper
2 tablespoons olive oil
¼ cup finely chopped shallots
1 teaspoon chopped garlic
2 cups drained chopped canned tomatoes
2 tablespoons fresh basil, chopped
½ cup grated Pecorino cheese
1 small focaccia bread cut in 8 pieces
Combine oil, vinegar, garlic, shallots and mustard in a bowl. Brush over mushrooms. Season and marinate for one hour.
Heat oil in pan on medium-high heat. Add shallots and cook for about 2 minutes or until softened. Add garlic and tomatoes and cook for 5 minutes, stirring often. Add the basil. Sauce should be thick. Reserve.
Preheat barbecue to high. Grill mushrooms 3 to 4 minutes a side or until browned and tender. Place one mushroom on each piece of focaccia. Top with tomato confit and cheese. Decorate with onion rings (see below).