The proprietor of a waterfront restaurant in Naxos Town slapped down a plate of grilled fish in front of me, and poured a golden elixir from a cruet into its steaming crevices. Mackerel with mustard sauce, it was, which turned out to be the most memorable fish dish I encountered during 10 days in Greece’s Cycladic islands.
That day had been a grueling one, for with our REI hiking group we had climbed two thousand feet to the top of Mt. Zas, the highest point in the islands. It was a hot enough day that goats clustered in the shade of hilltop walls to stay cool. We had also toured old Naxos Hora (Town), with its whitewashed pileup of flat-roofed buildings, gazed up at the Venetian Castle and admired the Arch of Apollo.
So I was more than ready to sit at our long communal table, sip wine and chat with fellow hikers. And what a joy to discover that this was to be a seafood feast that included head-on shrimp with rice and skate with an onion sauce. (There was also the Greek salad I wrote about in an earlier post, although not the version we had encountered elsewhere on the island, made with Naxos’ famous potatoes.)
Finally, the grilled mackerel with mustard sauce arrived. Our proprietor described its making, beginning with a dry rub of salt, pepper and oregano and setting the fish in the sun for an hour. Next, to the grill before the table side dousing with a pumped-up vinaigrette seasoned generously with mustard and garlic.
I love mackerel for its gutsy flavor and wonderful moist texture after cooking. It isn’t considered a premium fish that, like grouper and snapper, everyone gravitates to. So mackerel isn’t necessarily easy to find, but worth seeking out. Especially Spanish mackerel, a migratory fish to be found in the Northeast in summer.
In Florida, I’ve been told mackerel is plentiful except for December and January. Because it’s winter here, the mackerel I found was frozen, at a St. Petersburg place called Mastry’s, and it was whole, so we thawed and filleted it ourselves.
If you come up mackerel free, this sauce goes well with any fish that can stand up to dry heat, whether firm white fish such as snapper and grouper, or oilier species such as blue fish and mullet. It would be good with salmon or tuna, too.
To serve individual whole fish, as shown in the photo, choose whole mackerel or other scaled and gutted fish weighing one pound each or a little less (the yield will be about half a pound). Ask your vendor to cut off the head and butterfly the fish or do it yourself–here’s a site that tells you how.

Some Greek seafood dishes remind me of southern Italian cooking, but I've never tasted one quite like this in Italy.
- Coarse sea salt or kosher salt
- Freshly ground black pepper
- 1 teaspoon dried oregano
- 1½ pounds mackerel fillets*
- Extra virgin olive oil
- 1 tablespoon fresh lemon juice
- 1 tablespoon Dijon mustard
- Zest of ½ lemon
- 1 garlic clove cut in slivers
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Combine 1½ teaspoons salt, ¼ teaspoon pepper and the oregano in a small dish. Rub over surface of fish. Let stand at room temperature for an hour.
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In a blender or mini-blender container, combine 1/3 cup olive oil with the lemon juice, mustard, zest and garlic. Blend until smooth and emulsified. Season with salt and pepper (lightly, because the fish has been seasoned), and blend briefly.
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Set oven on broil or prepare a hot fire on grill. Place fish skin side down on a well-oiled grill pan in top third of oven or directly on a clean, oiled grill grate. Broil or grill until just cooked through, 8 to 10 minutes.
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Arrange fish on a platter or plates. Drizzle with mustard sauce.
* Alternatively, choose other fish that stand up to the heat of an oven or grill, such as snapper or grouper. More strongly flavored fish such as mullet or bluefish would be good choices as long as they are extremely fresh.