Step 1

Heat the grill. Heat an outdoor grill for direct, medium-high heat, about 400ºF. Meanwhile, prepare the sauce and season the swordfish.

Step 2

Prepare the sauce. Prepare the following, adding them all to a small bowl: Finely grate the zest of 1 medium lemon, then grate 1 garlic clove. Juice the lemon until you have 2 tablespoons juice. Finely chop until you have 2 tablespoons fresh mint leaves and 2 tablespoons fresh parsley leaves. Add 1/3 cup olive oil, 1/2 teaspoon of the kosher salt, and 1/4 teaspoon red pepper flakes if desired, and whisk to combine.

Step 3

Season the swordfish. Pat 4 swordfish steaks dry with paper towels, then place on a large plate. Transfer 2 tablespoons of the sauce into a small bowl and brush the swordfish steaks on both sides with the sauce. Reserve the remaining sauce for serving. Season the swordfish all over with the remaining 3/4 teaspoon kosher salt.

Step 4

Grill the swordfish. Scrape the grill grates clean if needed. Oil the grill grates with a paper towel dipped in olive oil. Place the swordfish on the grill, cover, and cook until grill marks appear on the bottom and the fish releases easily from the grill, about 5 minutes. If it sticks, cook a minute or two longer and try again.

Step 5

Flip the swordfish. Flip the fish, cover, and continue grilling until desired doneness, 2 to 4 minutes more. The internal temperature of the swordfish should be 130°F for medium, 135°F for medium-well, or 140ºF for well-done.

Step 6

Rest and serve the swordfish. Transfer the swordfish to a clean plate and let rest for 2 to 3 minutes. Serve with the remaining sauce spooned on top.