Sort of a Hero Sandwich
To transport this sandwich, place it on a round board or flat plate, and wrap tightly in plastic. Unwrap and slice just before serving.
1 large round loaf bread
6 large portobello mushrooms, stems trimmed to 1/2 inch
Olive oil, for brushing
Salt and freshly ground black pepper
1 large fennel bulb, thinly sliced
7 medium tomatoes, cored and sliced
1 small red onion(4 ounces), peeled, thinly sliced,...