Using a sharp knife, small dice the ahi. Turn the diced tuna in a mixing bowl. Season the tuna with salt and pepper.
In a small mixing bowl, whisk the oil, shallots, parsley, mustard, and lemon juice. Season with salt and pepper. Toss the diced tuna with the vinaigrette and mix thoroughly. Season the avocados with salt and pepper.
To assemble, spoon the Wasabi Creme fraiche in the center of the plate. Place 1 wonton in the center of the sauce. Spread 2 ounces of the tartar over the wonton. Sprinkle the avocados over the tartar. Place another fried wonton on top of the avocados. Spread 2 ounces of the tartar over the wonton. Sprinkle the avocados over the tartar. Top the sandwich with one fried wonton. Garnish the wontons with the red onions, caviar and chives. Repeat the process for the other three sandwiches.
In a small bowl, whisk the wasabi powder into the creme fraiche, smoothing all the lumps. Let creme sit for at least 1 hour, covered and refrigerated, to let the flavor bloom.