Halibut fillets can easily dry out when seared on the stovetop or broiled a minute too long in the oven, so to keep the fish moist in this recipe, we bake it in a spicy sauce. We switched up the usual pasta served alongside puttanesca with crunchy crostini instead. First toast the bread, then make the sauce by adding anchovies, red pepper flakes, tomatoes, capers, and olives to sautéed onions and cooking everything until the flavors blend. Put the sauce in a baking dish, nestle the fish in the sauce, and bake for a quick 15 minutes. Serve the halibut and sauce over the crostini with a crunchy green salad.
Special equipment: You’ll need a pastry brush for this recipe.
Game plan: The sauce can be prepared through step 2, cooled, and refrigerated for up to 4 days before proceeding with the rest of the recipe. The bread can be prepared up to 1 day in advance and kept in an airtight container at room temperature.
For the crostini:
12 ounces crusty Italian bread, cut into 1/2-inch-thick slices
Heat the oven to 450°F and arrange a rack in the middle.
While the oven heats, arrange the bread slices in a single layer on a baking sheet. Very lightly brush the tops of the bread with half of the oil. Flip the slices over and brush with the remaining oil. Season the tops with salt and pepper.
Bake until the bread is toasted and crisp on top, about 10 to 13 minutes. Meanwhile, make the sauce.
For the sauce and fish:
Heat the oil in a medium saucepan over medium-high heat until shimmering. Add the onions, garlic, and measured salt and cook, stirring occasionally, until the onions have softened, about 3 minutes. Add the anchovies and red pepper flakes and cook 1 minute more.
Add the tomatoes, olives, capers, and water, stir to combine, and bring to a simmer. Reduce the heat to medium low and simmer until the flavors have combined and the sauce has thickened slightly, about 15 minutes.
Spread 1 cup of the sauce in a 13-by-9-inch baking dish and add the fish in a single layer. Pour the remaining sauce over the fish and cover the dish tightly with aluminum foil.
Bake until the fish is just cooked through, about 15 minutes. Serve immediately with the crostini.