You can use any fish like bass, hake or haddock in place of the cod
3 pounds Yukon Gold potatoes
3 tomatoes very thinly sliced
2 1/4 chopped thyme
3 shallots, peeled and cut into very thin rounds (about 3/4 cup)
Salt and pepper
4 skinless cod fillets about 5 ounces each
12 very thin lemon slices
Step 1: Preheat oven to 425-degrees. Using a mandoline, slice potatoes about 1/8 inch thick.
Step 2: Drizzle 1 tablespoon oil in a shallow 3-quart lidded casserole dish.
Step 3: In slightly overlapping circles, alternate one-third each of potatoes, tomatoes, and shallots. About 1 tomato and shallot slice for every 5-6 potato slices. Drizzle with 1 tablespoon oil, scatter with one-third of thyme leaves and season with salt and pepper.
Step 4: Roast, covered until potatoes are knife tender, about 50 minutes. Season fish with salt and pepper: place lemon slices over potatoes and top with fish. Drizzle with remaining oil, thyme. Cover and roast until fish is cooked, 12-15 minutes. Let cool slightly before serving.