To prepare the namasu, in a bowl, combine the vinegar, sugar and ginger and stir until the sugar dissolves. Add the cucumber and carrots and marinate in the refrigerator for at least 2 hours, or overnight.
To prepare the aioli, in a blender, combine the plain aioli, oil, and spinach and puree' until smooth. Refrigerate until needed.
To prepare the mousse, in a small saute' pan over medium heat, melt the butter. Add the shallot and sweat for about 45 seconds, or until translucent. Let cool and transfer to a food processor. Add the lobster, egg white, and salt and puree' until smooth. With the machine running,slowly add the cream in a steady stream until fully incorporated; do not overmix. Refrigerate until needed.
To prepare the crab cakes, in a saute' pan over medium-high heat, heat 1 tablespoon of the vegetable oil. Add the celery and onion and saute' for 2 minutes, or until the onion is translucent. Chill. Transfer to a bowl, add the mousse, parsley, and crab meat and mix well. Divide the mixture into 8 portions and form into balls.
Place the flour on a plate. Roll the balls in the flour until lightly coated. In a bowl whisk together the egg and milk. Place the panko in a large plate. Dunk the crab cake balls in the egg mixture and then roll in the panko to cover. Repeat the egg and panko steps. Place a 2-inch cookie cutter on a work surface and form each ball into the round shape of the cookie cutter. Refrigerate for at least 10 minutes.
In a deep fryer or large sauce-pan, heat about 3 inches of vegetable oil to 350 degrees. Add the crab cakes and deep-fry for about 1 minute, or until they rise to the surface of the oil and turn golden brown. flip over and cook for 1 minute, or until golden brown.
To serve, divide the aioli among individual plates. Place 2 crab cakes on top of the aioli. Using a slotted spoon, remove the cucumber, carrot, and ginger from the marinade and serve next to the crab cakes.