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Grilled Tuna and Peppers with Caper Vinaigrette

This vibrant grilled tuna and peppers with caper vinaigrette is a wonderful example of Mediterranean-style cooking, focusing on high-quality ingredients and simple techniques. The meaty texture of the sushi-grade tuna steaks pairs beautifully with the mild sweetness of the charred Italian fry peppers. Finished with a sharp, salty dressing of citrus, mustard, and capers, this dish offers a sophisticated balance of flavours that feels surprisingly light yet deeply satisfying.

As a nutritious, diabetes-friendly main course, this recipe is naturally low in carbohydrates and rich in heart-healthy omega-3 fatty acids. It is ideal for a quick midweek dinner or a light weekend lunch during the warmer months. Serve the tuna just pink in the middle alongside a crisp green salad or some steamed seasonal greens for a complete, wholesome meal that is as healthy as it is delicious.

Continue reading below

Ingredients for Grilled Tuna and Peppers with Caper Vinaigrette

  • 350g Italian fry peppers (light green)

  • 2 (3/4-lb) sushi-grade tuna steaks (1-inch thick)

  • 1 1/4 teaspoons salt

  • 1 teaspoon black pepper

  • 1 1/2 tablespoons fresh lemon juice

  • 1/2 teaspoons Dijon mustard

  • 60ml olive oil

  • 1 1/2 tablespoons small capers in brine, drained and chopped

  • 2 tablespoons chopped fresh flat-leaf parsley

How to make Grilled Tuna and Peppers with Caper Vinaigrette

Prepare gas grill for cooking over direct high heat.

While grill heats, cut peppers lengthwise into quarters, discarding stems and seeds. Trim ends so that quarters lie flat.

Sprinkle tuna all over with 1 teaspoon salt and 1/2 teaspoons pepper. Cook tuna and peppers on lightly oiled grill rack, turning over once, until tuna is pink only in centre and peppers are just tender, 4 to 6 minutes total (peppers may take longer than tuna). Transfer tuna and peppers as cooked to a serving plate.

While tuna cooks, whisk together lemon juice, mustard, and remaining 1/4 teaspoons salt and 1/2 teaspoons pepper in a small bowl, then add oil in a slow stream, whisking until emulsified. Whisk in capers and parsley.

Serve tuna topped with peppers and caper vinaigrette.

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.

  • 17 Jan 2026 | Originally published

    Authored by:

    UK recipe editors

    Peer reviewed by

    UK recipe editors
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