Grind the sushi nori in a coffee grinder or mini food processor until it is the consistency of a powder.
Mix all remaining ingredients for the Blackening spice mix.
Reserve until just before cooking the tuna steaks
wasabi hollandaise sauce
Place a drop of cold water into a medium sized stainless steel mixing bowl on top of a suitable saucepan with boiling water inside. This is creating a double boiler with the bowl as the top half.
Add egg yolks and lemon juice to the mixing bowl, whisk with a thin wire whisk until the eggs are the consistency of medium custard. If the eggs start to cook too much, remove from the heat.
When the eggs are a custard-like consistency, whisk in the clarified butter in a thin stream until incorporated.
Mix the honey, wasabi powder, and rice vinegar in a small bowl until well incorporated and then add to the hollandaise sauce. Mix until well blended and season to taste with kosher salt.
Mix all ingredients and mixing just to incorporate with a wire whisk.
Do not over mix the batter, it can be slightly lumpy. Let it rest for at least ½ hour before using.
Fry the crabmeat by placing the lump crab in a bowl, adding the tempura batter, carefully mixing to coat, then removing the crab with a fork and dropping into a 350 degree F deep fat fryer until crisp.
Drop the crab in separate pieces so it will not stick together in the batter. Season with Kosher salt immediately upon removing from the fryer. Hold warm in a low oven until needed for up to about 10 minutes.
Coat the top and bottom of the tuna steak with the Asian blackening spice. Preheat a cast iron or heavy bottomed skillet on high heat until very hot, then carefully add clarified butter and place the tuna into the pan. Sear until you have formed a crust, then turn and cook the other side until similarly crusted. This should take about 1 minute per side and the tuna will be rare at this point. To cook to a higher degree of doneness, reduce the heat to medium and continue to cook on each side until it is to individual liking. Steam the asparagus and griddle the tomatoes while the tuna is cooking.
Steam the asparagus in the microwave or in a steamer until it is bright green and al dente. It should retain some crispness. Season with Kosher salt and black pepper immediately.
Season tomato slices with kosher salt and black pepper, then a few drops of olive oil. In a preheated non-stick pan or pancake type griddle, cook the tomato slices until lightly browned on each side.
Using a spatula, remove the tomato slices and place three slices in the center of each of four large dinner plates
Slice the tuna on an extreme angle from top corner to opposite bottom corner. Place on the tomatoes in the center of the plates.
Arrange the asparagus spears, tips upward on each plate, leaning on the tuna.
Carefully pour 1/4 cup of wasabi hollandaise sauce over the tuna and asparagus (mostly down the center, so as not to hide the tuna).
Finally, place three tempura fried crab pieces atop the tuna, asparagus, and sauce.