Why It Works
- Thick swordfish steaks aren't traditional in this dish, but they aren't nearly as likely to overcook as thin ones.
- Cooking the swordfish mostly on one side allows for good browning and flavor development without overcooking.
When I grilled some swordfish steaks for friends this past summer, one declared it the best swordfish she'd ever had, then asked me for my secret. I shrugged, pointed up the road towards the fishmonger where I'd bought it, and said, "That's a great fish market, and they know how thick to slice a piece of swordfish." And let me tell you, those swordfish steaks were really thick.
Choosing the Steaks
This is one way in which I diverge from the culinary norms of Italy, where, at least when I've seen it, the swordfish is often cut into much thinner steaks measuring less than one inch. To me, a swordfish steak is just like any other steak: It dries out when you overcook it, so you need a piece that's thick enough that it doesn't grow dry and chalky in the time it takes to put a good sear on it. That means a swordfish steak that's at least one-and-a-half inches thick.
There are plenty of other ways I'm more than willing to borrow from Italy, though, and this easy, flavorful tomato sauce is one of them. Served with swordfish, the dish goes by various names, including agghiotta di pesce spada ("swordfish done in the glutton's style"), pesce spada alla messinese ("Messina-style swordfish"), and the more general pesce spada alla siciliana ("Sicilian-style swordfish"). I can't figure out why this particular dish got linked with a glutton, given that it's relatively light fare. Maybe some gluttons are more restrained than me.
Gluttons aside, it's delicious. This sauce varies from cook to cook, but most versions are built on olive oil, fresh tomatoes, garlic or onion, briny olive, and salty capers. Some recipes add pine nuts, some raisins, and some both. In the winter months, you can still make this just as easily with canned tomatoes.
To cook the swordfish, I use a technique called unilateral cooking, in which a piece of food is cooked mostly or entirely on just one side. It can be particularly helpful with many kinds of fish, where the flesh can reach doneness before the surface has taken on good color. A flour dredge also helps build color on the steaks.
Making the Sauce
After cooking the fish, you make the sauce right in the same skillet. I tried making it with both fresh and canned tomatoes, and preferred the fresh in this context, though as I wrote above, canned still works well out of season (it's also what's shown in the photos because they were taken in the winter).
I also played around with various inclusions, preparing the sauce with either garlic or onion, and with and without both pine nuts and raisins. The raisins are a common Sicilian ingredient in savory dishes (e.g., caponata and spaghetti con le sarde), frequently helping to create the agrodolce ("sweet-sour") flavor that's so common in Southern Italian cooking. I decided to leave them out of the final version of this recipe, since I didn't want too strong of a sweet-sour flavor, instead taking a more subtle approach by relying on sweet sautéed onions and the tomatoes to provide that fruity note. If you want, and if your tomatoes will be improved by it (they can vary so much in flavor and tartness, so it will really depend on what you're using), you can finish this sauce with a teaspoon or two of red wine vinegar and a pinch of sugar; totally optional, but worth considering when you taste the sauce before serving.
Vinegar-Brined vs. Salt-Packed Capers
As for the capers, I know it's a lot easier to find them packed in vinegar, and if that's all you can find, you can use that product here. But I'd encourage everyone to track down Italian salt-packed capers if at all possible. They're more salty than they are pickle-y (the olives add enough brine to the sauce on their own), and have a more pronounced vegetal flavor that works so well in this sauce.
In the end, the sauce should be fruity and subtly sweet, with mild pops of briny olives, salty capers, and nutty toasted pine nuts. And easy as it is, it's enough of an act of cooking that when your friends ask you how you made such delicious swordfish, you'll have a little more to say than just praising the fishmonger.
- 2 pounds (910g) swordfish steaks, 1 to 1 1/2 inches thick, divided into four 8-ounce (225g) portions
- Kosher salt and freshly ground black pepper
- All-purpose flour, for dredging (about 1/2 cup)
- 5 tablespoons (75ml) extra-virgin olive oil, divided
- 1 medium (8-ounce; 225g) red onion, diced
- 1 1/2 pounds (680g) small tomatoes, quartered, or one 28-ounce can whole peeled tomatoes with juices, tomatoes roughly chopped (see notes)
- 2 tablespoons (3/4 ounce, 21g) salted capers, rinsed of excess salt (see notes)
- 1/2 cup (2 ounces; 57g) pitted mild green olives, such as Castelvetrano, halved lengthwise
- 2 tablespoons (1 ounce; 28g) pine nuts, toasted (see notes)
- 2 tablespoons (1/4 ounce; 8g) minced flat-leaf parsley leaves and tender stems
- Red wine vinegar and/or granulated sugar, to taste (optional)
Season swordfish all over with salt and pepper. Spread flour on a plate in an even layer. Working one piece at a time, dredge swordfish steaks all over, shake off excess flour, then transfer to a platter.
In a large 12-inch stainless-steel skillet or saute pan, heat 2 tablespoons (30ml) oil over medium-high heat until shimmering. Working in batches if necessary, add swordfish steaks and cook until well browned on first side, about 5 minutes. Flip swordfish steaks and cook until an instant-read thermometer inserted in the center registers 130°F (54°C) for medium, 135°F (57°C) for medium-well, or 140 to 145°F (60 to 63°C) for well-done, about 2 minutes (the timing will depend on the thickness of the swordfish steaks; note that it's important to get good color on at least one side, hence the longer cooking time on the first side). Return swordfish to the platter.
Wipe out skillet and return to medium-high heat. Add remaining 3 tablespoons (45ml) oil to the skillet along with the onion. Cook, stirring and scraping the bottom of the pan, until onion has softened but not browned, about 4 minutes. Add tomatoes, capers, and olives and cook, stirring, until tomatoes have broken down and their liquid has thickened, about 5 minutes. Season with salt. If desired, add 1 or 2 teaspoons red wine vinegar and a pinch or two of sugar to balance the sauce's flavor; whether or not you decide to do this will depend on the flavor of the tomatoes you're using, and how far into agrodolce ("sweet-sour") territory you want to push the sauce.
Reduce heat to medium. Stir in pine nuts and parsley, then return swordfish to the pan, nestling it into the sauce and cook until warmed through. Serve hot, warm, room temperature, or chilled.
We recommend fresh tomatoes for this dish, if you can find decently ripe ones. If not, canned tomatoes work well as a substitute.
Salted capers should be washed free of any salt clinging to them and then soaked for at least 15 and up to 30 minutes in ample fresh water before draining and using.
To toast pine nuts, place on a microwave-safe plate and microwave at 1-minute intervals, stirring in between, until golden brown and toasty, about 3 minutes total. Alternatively, toast by tossing the nuts over medium-low heat in a dry skillet, stirring constantly, until toasted, about 5 minutes total.
This recipe can be prepared up to 1 day in advance and kept refrigerated in an airtight container; it's delicious chilled or at room temperature. Longer storage can lead to a decline in the quality of the swordfish's texture, even if it's technically still safe to eat, so we don't recommend it.