Blackened Ahi with Soy-Mustard Sauce

Blackened Ahi with Soy-Mustard Sauce Recipe

The technique of blackening fish was popularized by Paul Prudhomme in the 1980s, when Cajun cuisine hit the national limelight. This is my Pacific Rim version, and it’s been on the menu ever since I opened my first Roy’s restaurant in Hawaii in 1988. It’s still one of our most popular appetizers.

Ground sandalwood is the powdered root and wood of a large tree native to the Pacific Islands and eastern Asia. It is used for both its red color and its aromatic quality for seasoning. It is available in well-stocked Asian markets or can be ordered direct from Yogi brand in New Orleans, at (504) 486-5538.–Roy Yamaguchi with John Harrisson

Blackened Ahi with Soy-Mustard Sauce Recipe

  • Quick Glance
  • 35 M
  • 1 H
  • Serves 4


  • For the soy-mustard sauce
  • 1/4 cup mustard powder, preferably Colman’s
  • 2 tablespoons hot water
  • 2 tablespoons rice wine vinegar
  • 1/4 cup soy sauce
  • For the beurre blanc
  • 1/2 cup dry white wine
  • 2 teaspoons white wine vinegar
  • 1 teaspoon fresh lemon juice
  • 1 tablespoon minced shallot
  • 2 tablespoons heavy cream
  • 1/2 cup cold unsalted butter, chopped
  • 1/4 teaspoon salt
  • Freshly ground white pepper
  • For the blackening spice
  • 1 1/2 tablespoons paprika
  • 1/2 tablespoon cayenne pepper
  • 1/2 tablespoon pure chile powder
  • 1/4 tablespoon freshly ground white pepper
  • 1/2 tablespoon ground sandalwood (optional)
  • For the tuna
  • 8 ounces ahi tuna fillet, about 2 inches thick and 5 inches long
  • 2 tablespoons olive oil
  • 3/4 cup warm Beurre Blanc
  • For the garnish
  • 2 to 3 tablespoons pink pickled ginger
  • 1 ounce daikon sprouts
  • 1/2 tablespoon black sesame seeds, toasted


  • Make the soy-mustard sauce
  • 1. Mix the mustard powder and hot water together in a cup to form a paste. Let sit for a few minutes to allow the flavor and heat to develop. Add the vinegar and soy sauce, mix together, and pass through a fine-mesh sieve into a bowl. Cover and refrigerate for at least 1 hour to allow the flavors to develop.
  • Make the beurre blanc
  • 2. Combine the wine, vinegar, lemon juice, and shallot in a heavy stainless steel saucepan. Bring to a boil over medium-high heat and cook to reduce the liquid until it becomes syrupy.
  • 3. Add the cream and cook to reduce by half. Decrease the heat to low and gradually add the butter, stirring slowly; do not whisk. Take care not to let the mixture boil, or it will separate. When the butter is incorporated, season with salt and pepper to taste, and strain through a fine-mesh sieve into the top of a double boiler. Keep warm over barely simmering water.
  • Make the ahi
  • 4. Mix all of the blackening spice ingredients together on a plate. Dredge the ahi in the spice mixture on all sides.
  • 5. Heat the olive oil in a nonstick skillet over high heat and sear the ahi for 15 to 30 seconds on each side for rare, 1 minute on each side for medium-rare, or to the desired doneness. Remove the ahi and cut into 20 thin slices.
  • 6. For each serving, arrange 5 slices of ahi in a fan, pinwheel, or cross shape on the plate. Spoon or drizzle a little of the Soy-Mustard Sauce around the tuna, and then spoon or drizzle the Beurre Blanc around.
  • 7. To garnish, arrange a small mound of the pickled ginger next to the fish and top with the daikon sprouts. Sprinkle the sesame seeds over the Soy-Mustard Sauce.
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