Ingredients

• 1 pound small Yukon gold potatoes, sliced about inch thick
• 1 small onion, sliced
• 1 clove garlic, minced
• 3 tablespoons extra-virgin olive oil
• 1/4 teaspoon red pepper flakes
• Kosher salt
• 4 skinless center-cut wild cod fillets (about 6 ounces each)
• 1/4 teaspoon finely grated lemon zest, plus 2 tablespoons lemon juice
• Freshly ground pepper
• 1 teaspoon chopped fresh thyme
• 1/4 cup pitted kalamata olives, coarsely chopped
• 1 15-ounce can cherry tomatoes
• 2 tablespoons unsalted butter, at room temperature
• 1 tablespoon chopped fresh chives

Instructions

1. Toss the potatoes, onion and garlic with 1 tablespoon olive oil, the red pepper flakes and 1/4 teaspoon salt in a bowl. Put the cod on a plate; drizzle with the lemon juice and season with salt, pepper and the thyme.
2. Preheat the oven to 425 degrees F. Tear off four 16-inch sheets of parchment paper. Make the packets (see photo gallery): Arrange about one-quarter of the potato mixture on one sheet of parchment; top with a cod fillet and about one-quarter each of the olives and tomatoes (along with some liquid from the can). Drizzle with 1/2 tablespoon olive oil. Seal as directed. Repeat to make 3 more packets; divide between 2 baking sheets.
3. Transfer to the oven and bake until the parchment puffs and the liquid is bubbling, about 25 minutes. Let rest 5 minutes before opening.
4. Meanwhile, mix the butter, chives, lemon zest and a pinch of salt in a small bowl. Carefully open the packets; top with the chive butter.
5. Photograph by David Malosh