Roy's Signature Blackened Ahi with Soy Mustard Sauce

Roy's Signature Blackened Ahi with Soy Mustard Sauce
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Recipe for Roy's Signature Blackened Ahi with Soy Mustard Sauce. This is one of the most popular appetizers from Chef Roy Yamaguchi’s restaurants.


  • Soy-Mustard Sauce:
  • 1/4 cup mustard powder, preferably Coleman's®
  • 2 tablespoons hot water
  • 2 tablespoons rice wine vinegar
  • 1/4 cup soy sauce
  • 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)
  • 8 ounces ahi tuna filet, about 2 inches thick and 5 inches long
  • 2 tablespoons olive oil
  • 3/4 cup warm beurre blanc sauce (see recipe links below)
  • Garnish:
  • 2 to 3 tablespoons pink pickled ginger
  • 1/2 tablespoon black sesame seeds, toasted
  • 1 ounce daikon sprouts


  1. Serves 4 as an Appetizer
  2. To prepare the mustard sauce, 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.
  3. Prepare the beurre blanc and warm in the top of a double boiler.
  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 skillet over high heat and sear the ahi for 15 to 30 seconds on each side for rare, 1 minutes 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. 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.