Heat the oven to 400 degrees. Slice bread in half lengthwise. Toss remaining ingredients in a bowl until the onion slices are separated and all the ingredients are evenly distributed. Cover both sides of bread with a even layer of this mix. Bake the bread at 400 degrees directly on the rack of the oven until the bread is crispy and the top is lightly browned, about 8 minutes. Remove bread carefully and let stand a few minutes before slicing crosswise into 2-inch pieces. Serve hot. Makes 8 servings.