In a saucepan, boil the potatoes in salted water to cover until tender,
about 30 minutes. Drain the potatoes, then peel and slice them.
Preheat an oven to 350 degrees. Pour 3 tablespoons of the olive oil into
an ovenproof earthenware dish. Arrange the potato slices in overlapping
concentric circles in the botton of the dish. Lay the fish on top of the
potatoes and sprinkle with rosemary and bread crumbs. Place the tomato
slices on the fish and season to taste with salt and pepper. Drizzle the
remaining 3 tablespoons olive oil over the top and pour in the wine. Bake
for 20 minutes. Serve hot directly from the dish.