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Caper-Rosemary Tuna with Herb Salad

This elegant caper-rosemary tuna with herb salad is a sophisticated yet simple dish that celebrates fresh, Mediterranean flavours. The meaty texture of the tuna steaks pairs beautifully with a zesty marinade of lemon, rosemary, and briny capers, providing a savoury depth without the need for heavy sauces. It is a wonderful choice for a light summer lunch or a quick evening meal that feels truly special.

As a diabetes-friendly main course, this recipe focuses on heart-healthy fats from extra-virgin olive oil and high-quality lean protein. The accompanying herb salad, featuring flat-leaf parsley and aromatic tarragon, adds a refreshing crunch and a wealth of antioxidants. This homemade dish is as nutritious as it is flavourful, making it a reliable staple for healthy eating.

Continue reading below

Ingredients for Caper-Rosemary Tuna with Herb Salad

  • 90ml extra-virgin olive oil

  • 60ml fresh lemon juice

  • 2 tablespoons drained capers

  • 20ml liquid from capers in jar

  • 20ml finely grated lemon peel

  • 2 teaspoons finely minced fresh rosemary

  • 1 teaspoon fine sea salt

  • Large pinch of dried crushed red pepper

  • Pinch of sugar

  • 1 small onion, quartered through core, thinly sliced crosswise (1 scant cup)

  • 6 6-to 200g 1-inch-thick tuna steaks

  • 2 cups (loosely packed) fresh Italian parsley leaves

  • 1/2 cup (loosely packed) assorted fresh herb leaves (such as tarragon, chervil, oregano, celery leaves, and marjoram)

  • 1 teaspoon extra-virgin olive oil

  • 1 teaspoon fresh lemon juice

How to make Caper-Rosemary Tuna with Herb Salad

Whisk first 9 ingredients in large bowl. Stir in onion. Transfer mixture to resealable plastic bag. Add tuna and seal bag, releasing any excess air; turn to coat. Let marinate at room temperature 1 hour, turning occasionally. (Alternatively, chill 4 hours, turning occasionally, then allow to return to room temperature before continuing.)

Mix parsley and other herbs in large bowl. Sprinkle with salt and pepper. Cover and chill while preparing fish.

Prepare barbecue (high heat). Brush grill rack with oil. Remove tuna from bag, scraping excess marinade back into bag. Grill until grill marks appear but tuna is still rare in centres, 2 to 3 minutes per side. Transfer to plate.

Pour marinade into small saucepan. Bring just to simmer.

Drizzle 1 teaspoon oil and lemon juice over herb salad; toss to coat. Place 1 tuna steak on each plate. Spoon warm marinade over. Divide herb salad among plates.

Disclaimer

While every effort has been made to ensure the information is accurate and up to date, individual needs may vary and dietary requirements can differ based on personal health conditions. Always check food labels and allergen information before preparing or consuming any recipe. If you have specific health concerns, allergies, intolerances, or are following a medically prescribed diet, seek advice from your GP, pharmacist, or a registered dietitian before making significant changes to your diet or lifestyle.

Article history

The information on this page is peer reviewed by qualified clinicians.

  • 16 Jan 2026 | Originally published

    Authored by:

    UK recipe editors

    Peer reviewed by

    UK recipe editors
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