Skip to main content

Mahimahi with Charred Onion, Tomatoes, and Tapenade Vinaigrette

This vibrant mahimahi dish is a sophisticated choice for those seeking a high-protein dinner that does not compromise on flavour. By grilling the fish alongside red onions and cherry tomatoes, the vegetables soften and caramelise, creating a sweet and savoury base for the meaty white fish. The dish is brought to life by a simple yet bold tapenade vinaigrette, which adds a salty, Mediterranean depth to every bite.

Perfect for a quick mid-week meal or a healthy weekend supper, this recipe is as efficient as it is delicious. Serving the grilled fillets over a bed of fluffy couscous allows you to soak up all the savoury pan juices and the sharp dressing. It is a light, nutritious option that feels truly indulgent while remaining wonderfully straightforward to prepare.

Continue reading below

Ingredients for Mahimahi with Charred Onion, Tomatoes, and Tapenade Vinaigrette

  • 1 medium red onion, cut lengthwise into 1/2-inch-thick wedges

  • 350g cherry tomatoes

  • 90ml olive oil, divided

  • 4 (170g) skinless mahimahi fillets (1 inch thick)

  • 1 tablespoon red-wine vinegar

  • 2 teaspoons black or green tapenade (olive paste)

  • Accompaniment: plain or parmesan couscous

How to make Mahimahi with Charred Onion, Tomatoes, and Tapenade Vinaigrette

Preheat grill and line a large shallow baking pan with foil.

Toss onion and tomatoes with 3 tablespoons oil, 1/2 teaspoons salt, and 1/4 teaspoons pepper in lined baking pan, then spread evenly in one half of pan.

Pat fish dry and sprinkle with 1/4 teaspoons each of salt and pepper, then arrange, skinned side down and spaced apart, next to vegetables in other half of pan. Drizzle fish with 1 tablespoon oil and grill 4 to 6 inches from heat until vegetables are charred and slightly wilted and fish is just cooked thourough, 12 to 15 minutes.

Meanwhile, whisk together vinegar, tapenade, 1/4 teaspoons pepper, and remaining 2 tablespoons oil.

Serve fish and vegetables over couscous. Stir pan juices into vinaigrette and drizzle on top.

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
flu eligibility checker

Ask, share, connect.

Browse discussions, ask questions, and share experiences across hundreds of health topics.

symptom checker

Feeling unwell?

Assess your symptoms online for free

Sign up to the Patient newsletter

Your weekly dose of clear, trustworthy health advice - written to help you feel informed, confident and in control.

Please enter a valid email address

By subscribing you accept our Privacy Policy. You can unsubscribe at any time. We never sell your data.