Bluefin Tuna in Mauritius: the black diamond of the sea

Around the world, one fish stands as an outright treasure: bluefin tuna. And among bluefin, the fish drawn from the icy waters of the Tsugaru Strait, off Ōma in Aomori Prefecture (Japan), carry a nickname that says it all — "the black diamond of the sea".

This guide explains why Aomori bluefin tuna became a world reference, what toro really is — the melting marbling behind its legend — and how to prepare it at home: seared, as tataki or grilled, without ever overcooking it.

Ōma bluefin tuna: a world reference

At the northern tip of Honshū, the small port of Ōma faces the Tsugaru Strait, the channel of cold, fast-moving water that separates Honshū from Hokkaidō. This is where some of the most sought-after bluefin tuna in the world are caught.

The reason lies in the environment. In these icy waters, the tuna develops a delicate fat, spread through the heart of the muscle, which gives it a melting texture and a depth of flavour that are simply incomparable. That is what sets Aomori bluefin apart and earns it, year after year, its reputation for excellence.

The marbling: the magic of toro

Just as a great cut of beef is read by its marbling, bluefin tuna is read by its own: those fine, pale threads of fat running through the flesh. In Japan, three main parts are distinguished:

• Akami — the leaner red flesh, with a clean, straightforward taste.
• Chū-toro — the medium marbling, balanced between the richness of the fat and the freshness of the flesh.
• Ō-toro — the most marbled part, taken from towards the belly: it is the one that literally melts in the mouth, so fine is the fat.

This fat is anything but heavy: developed in the icy waters of the Tsugaru Strait, it is delicate, silky, and dissolves in the heat like the marbling of a fine piece of meat. That is the whole magic of toro — and what makes Aomori bluefin tuna an exceptional product, of incomparable quality.

How to prepare it: seared, tataki, grilled

Bluefin tuna of this quality asks for very little. The key is never to overcook it: the flesh dries out quickly, and the right touch stays short and lively. Three preparations show it at its best:

• Seared (mi-cuit). A hot pan or griddle, a splash of oil, and you sear the steak for a minute a side: the outside colours and firms up, while the centre stays warm and melting.
• As tataki. Sear each face of the piece briskly, then slice it: the surface is cooked, the centre just warm. A dash of soy sauce, a little ginger, a few sesame seeds — the classic pairing.
• Grilled. Over coals or on a grill, a few minutes turning it just once. Keep the centre just pink to hold on to all the tenderness.

In every case, salt at the end of cooking and serve without waiting. Bluefin tuna is always eaten cooked or seared through: for safety, this guide does not recommend eating it raw or as sashimi.

Our bluefin tuna in Mauritius

Bringing Aomori bluefin tuna all the way to the island, done properly, comes down to careful logistics. Here's what Bon Manzé Maurice offers:

• Bluefin tuna from Ōma, Aomori (Japan) — the famous "black diamond of the sea", with its melting texture.
• A delicate fat born of the icy waters of the Tsugaru Strait, of incomparable quality.
• Delivered vacuum-sealed, cold chain maintained, anywhere in Mauritius.
• Guide price: Rs 3,300/kg, VAT included, confirmed by weight before delivery, subject to availability.
• A real person on WhatsApp, for quantity as much as for preparation.

Free delivery from Rs 1,500 · pay on delivery (cash or Juice MCB) · nothing is paid online · quantities limited per batch.

Bluefin tuna sits naturally within a fine selection of fresh fish in Mauritius — and, to vary the pleasure, our wild salmon guide is waiting for you.

Frequently asked questions