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This garlic herb sauce for tuna steaks is full of bright flavor! Parsley, lemon, and capers make a punchy pairing with the savory fish.

Sauce for Tuna Steak
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Looking to add flair to ahi tuna? Try this Garlic Herb Sauce for tuna steaks! This incredible green drizzle is full of bright flavor. Fresh parsley, lemon, and capers make a punchy pairing with the savory fish. It adds a Mediterranean-style flair to this buttery, mild fish. Once you’ve cooked your tuna steak to perfection, this sauce is ideal for stepping it up a few notches. Here’s what to know!

Ingredients in this sauce for tuna steaks

It’s often that Asian-style flavors are paired with ahi tuna, but this fish is also ripe for Mediterranean-style flavors as well. This sauce for tuna steak is a butter sauce that’s bright and tangy, with loads of flavor from each of the ingredients. Here’s what you’ll need:

  • Butter
  • Capers
  • Italian flat-leaf parsley
  • Lemon zest
  • Garlic
  • Dijon mustard
  • Salt
Sauce for Tuna Steak

Tips for making the sauce

This sauce for tuna steaks comes together quickly: but there are a few things to note about ease of preparation. Here’s what to keep in mind when preparing this sauce (or jump to the recipe below to get started!):

  • The sauce makes enough for 4 modest portions or 2 large. A little goes a long way here! You’ll only need a few drizzles on each tuna steak.
  • Prep the ingredients while the tuna steak comes to room temp. It’s best practice to leave ahi tuna steak at room temperature for about 20 minutes before cooking it. If you cook it straight from the fridge, the inside can be cold while the outside is fully cooked. Use this time to prep the ingredients for your sauce!
  • Make the sauce right before serving. Because it’s a butter sauce, it’s best to make the sauce directly before serving the tuna steaks so that the butter is perfectly melted. We don’t recommend making the sauce in advance, because the color of the herbs dulls during storage.
Sauce for Tuna Steak

How to buy and cook tuna steaks

Ahi tuna, aka yellowfin tuna or bigeye tuna, is a mild, lean fish commonly served as sushi, in poke bowls, or cooked rare or medium-rare.  Wondering best practices for selecting and cooking tuna steaks? Head over to How to Cook Tuna Steak for a tutorial!

More tuna steak recipes

Love a great piece of ahi tuna? Here are a few more tuna steak recipes you can make with this delicious buttery fish:

This sauce for tuna steak is…

Vegetarian and gluten-free.

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Sauce for Tuna Steak

Tuna Steak with Garlic Herb Sauce

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5 from 2 reviews

  • Author: Sonja Overhiser
  • Prep Time: 20 minutes
  • Cook Time: 5 minutes
  • Total Time: 25 minutes
  • Yield: 4 1x


This garlic herb sauce for tuna steaks is full of bright flavor! Parsley, lemon, and capers make a punchy pairing with the savory fish.



For the garlic herb sauce

  • 3 tablespoons salted butter
  • 2 tablespoons jarred capers, drained
  • ¼ cup fresh Italian flat-leaf parsley, finely minced
  • ½ teaspoon lemon zest
  • 1 whole garlic clove, peeled and smashed
  • ½ teaspoon Dijon mustard
  • 1 pinch kosher salt

For the tuna steaks

  • 4 steaks (1 pound) high quality ahi tuna (sashimi grade recommended; wild caught if you can find it*)
  • 1 tablespoon neutral oil
  • 1 ½ teaspoons kosher salt
  • Fresh ground black pepper


  1. Allow the tuna steak to come to room temperature by letting it stand for at least 20 minutes. (Use this time to prep the ingredients for the sauce!)
  2. Pat the tuna dry. Sprinkle it liberally with kosher salt and fresh ground black pepper on both sides to get a nice even coating.
  3. Heat the oil in a medium skillet over medium high heat. Add the tuna steaks and cook 1 to 2 minutes per side, until lightly browned on the outside but still rare the inside. The tuna will continue cooking while sitting. For a medium-rare tuna steak, the internal temperature should be 130 degrees Fahrenheit when measured with a food thermometer at the thickest point.
  4. Allow the tuna to cool for 3 minutes while you make the sauce.
  5. Melt the butter in a small saucepan or skillet over low heat. Once melted, add the capers (whole or chopped for a smoother sauce), finely minced parsley, lemon zest, the smashed garlic clove, Dijon mustard, and salt and cook until fragrant, about 3 minutes. Remove from heat and remove garlic clove.
  6. Slice the tuna against the grain into ½-inch slices and serve immediately with a few drizzles of the sauce.
  • Category: Main dish
  • Method: Stovetop
  • Cuisine: Seafood
  • Diet: Gluten Free

About the authors

Sonja & Alex

Hi, we’re Alex and Sonja Overhiser, married cookbook authors, food bloggers, and recipe developers. We founded A Couple Cooks to share fresh, seasonal recipes for memorable kitchen moments! Our recipes are made by two real people and work every time.

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  1. Teresa Baca says:

    Great recipe i loved the idea and did it today . I freeze the rest for next week

  2. Sophie Le Gaudiet says:

    What sides would go well with this dish?

  3. Shoshonna Clemons says:

    We don’t have capers, can we use something else?

    1. Sonja Overhiser says:

      Capers really make the sauce! But if you don’t have them, you can omit and add a pinch more salt.

  4. Bess says:

    The description mentions lemon but there’s none in the sauce recipe. Was lemon juice and/or zest supposed be included?

    1. Sonja Overhiser says:

      Great catch: lemon zest should be in the recipe. We’ve updated it accordingly! Thank you.

  5. Sonja Overhiser says:

    Let us know if you have any questions!