Southern Bluefin Tuna in a Mexican-style Black Bean, Pumpkin Seed and Chili Sauce with Rice
Every winter around Matariki, the Māori New Year, the deep waters of New Zealand come alive with Southern Bluefin tuna. After spawning in the Indian Ocean south of Java, the adults migrate to feed and rebuild their energy, dispersing across the southern oceans. The fish that reach our coastline mark the easternmost edge of this migration. They begin appearing in May and are in prime condition for fishing from June through August, before turning back toward the Indian Ocean to repeat the cycle.
For a few short weeks, coastal launching spots hum with early‑morning activity and the kind of excitement only a true seasonal catch can bring. Southern Bluefin is a special fish - rich, clean, almost buttery - and when it’s pulled from winter waters, its flavour is at its absolute peak. This year my boys launched at Waihau Bay on the East Coast of the North Island and were lucky enough to bring home an early fish.
I like to honour this beautiful tuna by keeping the cooking hot and quick: a flash‑fry is all it needs. The aim is a caramelised crust with a ruby‑pink centre that stays tender and silky. But Bluefin is generous in size, and even after sharing with friends and family, dreaming up ways to use it while it’s fresh can be a challenge!
This dish is based on one of my favourite Mexican‑style chilis - the kind I’d usually bulk out with summer courgettes and capsicums when the garden is overflowing. But it’s winter now, and those vegetables are either unavailable or far too expensive, so this version leans more into pantry staples and can also be made with canned tuna if you can't get hold of fresh. This recipe starts with dry‑roasted green pumpkin seeds, toasted until they pop and release their nutty aroma. Once cooled, they’re blitzed into a creamy pulp with half a can of tomatoes, garlic, and onion, then folded into the remaining tomato with canned black beans, chilli, and spices.
The result is a rustic, earthy sauce with gentle heat and a very New Zealand practicality and super easy to bulk out with more beans or rice to feed more people if necessary. Cooking with fresh Southern Bluefin Tuna really reminds us how lucky we are to live in New Zealand: wild food, seasonal rhythms, and flavours that don’t need much fussing to shine.
Watch this quick recipe tutorial here:
Method
(Serves 3-4)
1 tuna steak per person (or one large can of tuna in olive oil)
1 onion, peeled and finely diced
2 cloves garlic, peeled and crushed
Olive oil for frying
1/2 -3/4 cup dried pumpkin seeds
1 420gm can plain peeled tomatoes
1 420gm can black beans in brine
Dash of chili flakes
1 tsp oregano
1/2 tsp ground cumin
fresh red chili to decorate (if you have it)
Ground sea salt and black pepper
Fresh lime to decorate
3/4 - 1 cup white rice, cooked (allow 1/4 cup per person)
Method
Heat a fry pan over medium and dry‑toast the pumpkin seeds, turning them regularly so they don’t burn. They’ll deepen in colour and may start popping. Tip them into a bowl and set aside to cool.
Add a splash of oil to the same pan and sauté the onion and garlic until soft and fragrant. Add these to the pumpkin seeds and let everything cool completely.
In a blender, combine half the can of tomatoes with the cooled pumpkin seeds, onion, and garlic. Blitz to a creamy, rustic paste.
Start cooking the rice according to the packet directions.
Return the paste to the pan and add the black beans, a few dessertspoons of the bean brine, and your spices. Bring the mixture to a gentle simmer so the flavours can settle and warm through.
In a separate pan, heat olive oil over high heat and flash‑fry the tuna steaks. You want a quick sear — caramelised on the outside, still tender inside. You can keep the steaks whole or break them into chunky pieces and fold them through the sauce.
Add the cooked rice to the pan and half‑mix it so some grains stay white and some soak up the sauce.
Serve on warm plates with fresh chilli scattered over the top and lime wedges for squeezing.
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