Lemon Herb Cod Fillets With Crispy Potatoes

Adapted from Menu Cookbook from America's Test Kitchen

• Servings: 4 to 6.

Key to making this simple but special fish and potato combo is having a mandoline or ceramic slicer to make sure the potato slices are both thin and uniform.

Toss the potatoes with olive oil as you slice them so that they won't darken.  While this dish is perfect with cod it can also be made with another white fish such as haddock or hake.

Ingredients

• 6 tablespoons unsalted butter, softened
• 1 tablespoon minced fresh thyme
• 1 tablespoon grated lemon zest
• 1/4 teaspoon salt plus more for salting the potatoes and fish
• Freshly ground black pepper
• 6 thin slices of fresh lemon
• 3 pounds yukon gold potatoes, peeled and sliced 1/4 inch
• 2 large cloves garlic, finely minced or grated with a Microplane zester
• 4 tablespoons extra virgin olive oil
• 1 1/2 pound skinless cod fillets, about 1 to 1/2 inches thick, cut into 6 serving pieces

Directions

1. Preheat oven to 400° F. Using your fingers or a pastry brush, brush about 1 tablespoon of olive oil over the surface of a rimmed baking sheet or roasting pan.
2. Mash the butter with the thyme, lemon zest, 1/4 teaspoon salt, and several grinds of black pepper, using a fork. You can make this herbed butter in advance and chill until needed but bring it back to a softened state before using.
3. Using a mandoline, ceramic slicer, or the slicing blade of a food processor, cut the potatoes into thin and uniform slices, about 1/4-inch thick. Place in a large bowl and toss with 3 tablespoons olive oil and the minced or grated garlic. Use your clean hands to mix so to combine the potatoes and garlic and make sure that all the potato slices are coated with oil.
4. Place the potato slices into the oiled baking sheet, arranging them in a single layer and into tight, even rows, like the shingles on a roof. Season with a pinch or two of salt and several grinds of black pepper.
5. Roast until the potatoes are just tender and are becoming brown and crispy along the edges, about 30 minutes (rotate the pan halfway through to help the potatoes cook evenly).
6. Pat the cod dry with paper towels, season with salt and pepper, and rub about 2 tablespoons of the herb butter over the top of each fillet.
7. Arrange the pieces of cod on top of the potatoes, taking care to not move the arranged pieces of potato. Place a lemon slice on top of each piece of fish.
8. Roast the potatoes and fish for about 12 to 15 minutes (the time will vary with how thick the fish is), until the fish is opaque and can flake easily.
9. Serve portions by cutting a square of potatoes from around each piece of fish, as if the potatoes are like a little plate underneath each piece of fillet.
10. Serve immediately.