Swordfish With Herb Sauce

⏲ ~23 min total · prep 15 · cook 8 · 4 servings

By the KFI Test Kitchen · Tested & approved by Jason Lieu, KFI recipe editor

Published Sep 15, 2026 · Updated Sep 15, 2026

Ingredients

• 4 swordfish steaks (6 oz each), about 1 inch thick
• 1/2 tsp kosher salt
• 1/4 tsp coarsely ground black pepper
• 2 tbsp olive oil
• 1 cup fresh flat-leaf parsley leaves
• 1/2 cup fresh basil leaves
• 1 small garlic clove, smashed
• 2 tbsp capers, drained
• 3 tbsp lemon juice
• 1/4 cup extra-virgin olive oil
• Lemon wedges, for serving

Instructions

1. Pulse the parsley, basil, garlic, capers, and lemon juice in a mini food processor with 8-10 pulses — you want coarse flecks, not a smooth pesto — then stream in the 1/4 cup olive oil until the sauce is loose and spoonable. Set it aside to meld.
2. Pat the swordfish steaks dry with paper towels (a dry surface is what browns) and season both sides with the salt and pepper; let them sit 10 minutes.
3. Heat the 2 tbsp olive oil in a 12-inch heavy skillet over medium-high heat until it shimmers.
4. Lay the steaks in without crowding and sear undisturbed 4-5 minutes, until deep golden and they release from the pan on their own.
5. Flip and sear 3-4 minutes more, until an instant-read thermometer reads 130°F at the thickest point — opaque all the way through with just a blush at center.
6. Rest the steaks 5 minutes on a warm plate, then spoon the herb sauce over each and pass lemon wedges alongside.

Why this recipe works

• Coarse, not smooth Eight to ten processor pulses leave the parsley and basil in visible flecks. The sauce sits on the steak instead of running off the plate the way a blended pesto would.
• Dry surface, real sear Patting the steaks dry and salting 10 minutes ahead gives the pan something to grab. A wet surface steams; a dry one turns deep golden and releases on its own.
• Thermometer finish The steaks come off at 130°F and rest 5 minutes, landing opaque all the way through with a blush at center rather than going chalky.

Tips for making this recipe well

Wait for the shimmer

Heat the oil until it shimmers before the steaks go in. Oil that isn't ready gives you steaming and sticking instead of a crust.

Mind the crowd

A 12-inch heavy skillet holds four 6-ounce steaks with air between them. Crowding drops the pan temperature and the sear never forms.

Sauce has room

The sauce melds while the fish sears, and leftovers keep 3 to 4 days refrigerated. It's good on grilled chicken or stirred into white beans.

Lemon twice

Juice in the sauce, wedges at the table. A final squeeze over the rested steak lifts the herbs and thins the capers.

Rest it

Five minutes on a warm plate finishes the carryover. Cut too soon and the juices flood the plate instead of staying in the steak.

Serving suggestions

Forty minutes, one skillet, and a plate that reads like far more effort than it took, at 0.8 net carbs a serving. Spoon the coarse herb sauce over each rested steak and pass the lemon wedges; the capers handle the salting. The plate wants something plain beside it, since the sauce is strong: steamed green beans or cauliflower rice to catch what the sauce leaves behind. Serve it hot; swordfish is at its best in the minutes after resting, and it stiffens as it sits.

Storage and meal prep

Refrigerate leftover swordfish, tightly covered, for 3 to 4 days. It's best the day it's cooked; reheat gently in a low oven, since a hard reheat tightens the flesh further. The herb sauce keeps separately for 3 to 4 days and separates as it stands, so stir before spooning. We skip the freezer for the fish, which weeps as it thaws and pays for it in texture.

Variations worth trying

• Other steaks The sear and sauce work the same on tuna or mahi steaks about an inch thick.
• Caper forward Double the capers and cut the lemon juice to 2 tablespoons for a brinier sauce.
• On the grill Season as written and grill over high heat to the same 130°F internal temperature.
• Quiet heat Add a pinch of red pepper flakes to the processor with the herbs.

Frequently asked questions

Can I cook swordfish past 130°F?

You can, and 145°F is the widely cited safe temperature for fish. Expect a drier, flakier texture than the blush-at-center finish this recipe aims for.

No food processor?

Chop the herbs, garlic, and capers by hand, then whisk in the lemon juice and oil. You lose some evenness and little else.

How thick should the steaks be?

About an inch, which is what the 4-to-5-minute first sear assumes. Thin steaks dry out before they color.

Why rest the fish at all?

Five minutes lets the carryover finish and the surface cool slightly. The first cut off the heat floods the plate otherwise.

What's the carb count?

0.8 net carbs per serving. The herbs, capers, and lemon barely register.

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