Weber’s Grilled Swordfish with Jalapeño-Mint Butter

Delicious grilled fish steak garnished with chives, served with fresh tomatoes on a white plate.

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This recipe is taken directly from Weber’s official recipe library — Swordfish Steaks with Jalapeño-Mint Butter Sauce, developed by grilling author Jamie Purviance. It’s a straightforward direct-heat method that pairs seared steaks with a smoky, herb-flecked butter sauce, and it’s a solid baseline for learning swordfish technique before you start adjusting the seasoning to your own taste.

Swordfish is one of the more forgiving fish to put straight on the grate. The steaks are thick, dense and meaty enough to hold together without a basket or foil, so all you really need is a hot grill, a spatula, and a thermometer or a close eye on color. This version builds its flavor around charred jalapeños and fresh mint folded into melted butter, rather than a marinade, which keeps the prep quick.

Ingredients

For the jalapeño-mint butter sauce

  • 2 medium jalapeño chile peppers
  • 1/2 cup (1 stick) unsalted butter
  • 1/4 cup minced fresh mint leaves (from 8 to 10 sprigs)
  • 3 tablespoons fresh lemon juice
  • 2 scallions (white and light green parts only), thinly sliced
  • 1 teaspoon kosher salt, divided

For the swordfish

  • 4 swordfish steaks, each about 8 ounces and 1 inch thick
  • Extra-virgin olive oil
  • 1/4 teaspoon freshly ground black pepper
  • 4 lemon wedges

Method

  1. Set up the grill for direct cooking over medium heat, roughly 350-450°F (177-232°C).
  2. Clean the cooking grates, then grill the whole jalapeños directly over the heat, lid closed, until the skins blacken all over, about 10 minutes, turning occasionally. Transfer them to a bowl, cover with plastic wrap so they steam, and let them sit for about 10 minutes before peeling off the charred skin and removing the stems and seeds. Dice finely.
  3. In a small saucepan on the stove over medium heat, melt the butter until it’s frothy, then stir in the diced jalapeños, mint, lemon juice, scallions and half the salt. Keep it warm over very low heat while the fish cooks.
  4. Brush both sides of the swordfish steaks with olive oil and season evenly with the remaining salt and the pepper.
  5. Grill the steaks directly over medium heat, lid closed, turning once, until the center is just opaque but still juicy — about 8 to 10 minutes total.
  6. Spoon the warm butter sauce over the steaks and serve with lemon wedges.

Checking for Doneness Safely

Weber’s own cue for this recipe is visual — pull the steaks when the center looks “just opaque” but still juicy. That’s a reasonable way to judge swordfish by eye, but it’s worth backing it up with a thermometer. The FDA’s guidance for fin fish is to cook to an internal temperature of 145°F (63°C), or until the flesh is opaque and separates easily with a fork. If you’re cooking to time rather than temperature, checking the thickest steak with an instant-read thermometer near the end of the 8-to-10-minute window is the safer way to confirm it’s actually there, rather than relying on color alone.

Because swordfish steaks are usually cut to a fairly even thickness, they cook more predictably than a whole fillet with a tapered end — one more reason this cut is a good one to start with if you’re new to grilling fish.

A Few Practical Notes

Steak thickness matters more than most other variables here. A steak under an inch thick can go from underdone to dry in the time it takes to answer your phone, since there’s so little mass to buffer the heat. If your fishmonger’s steaks run thin, either shorten the cooking time and watch closely, or ask for a thicker cut — Weber’s recipe is built around roughly 1-inch, 8-ounce portions, and that thickness is part of why the timing works.

The jalapeño char step can be done well ahead: grill and peel the peppers earlier in the day, then just reheat the butter sauce while the swordfish cooks. That keeps the actual grilling stretch short and lets you focus on timing the fish itself, which is the part that actually needs your attention.

If you don’t want the heat, swap in a milder pepper or skip it and use the mint-lemon butter on its own — the base sauce technique (melted butter plus an acid and fresh herbs) works with most firm grilled fish, not just swordfish.

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