Cut the ahi into small dice and put it in a medium-size mixing bowl. Season with salt and pepper. Whisk the shallots, parsley, mustard, lemon juice, and olive oil together in a small mixing bowl and season with salt and pepper. Toss the tuna with the vinaigrette and mix well. Cover and refrigerate the mixture for at least 1 hour.
Season the avocado dice with salt and pepper.
Combine the sour cream with the wasabi mixture and season with salt and pepper.
To serve, place a wonton in the center of an appetizer plate. Spread about a tablespoon of the tartare on top of the wonton. Spoon a dollop of the wasabi cream on top of the tartare, then scatter around a little of the avocado and red onion. Top with a wonton and repeat with tartare, wasabi cream, avocado, and red onion. Top with a third wonton, then drizzle with sesame oil and dot with the caviar and chives. Repeat the process for the other 3 sandwiches.
Yield: 4 servings