Trim the hamachi filet, removing the bloodline. Thinly slice the filet against the grain into about 1/8” slices.
For the Almond Milk Foam:
Simmer the milk and toasted almonds for 10 minutes, then rest at room temperature for one hour. Strain the milk and return to a small pot. Add the almond oil and lecithin, and blend with the hand blender to combine. When ready to plate, buzz with a hand blender and scoop the foam onto the plates.
For the almonds, crack the outer green shell with the heel of a knife, trying not to bruise the nut inside. Peel away the shell and remove the nuts. If not using immediately, hold the fresh shelled almonds in milk. Cut the watermelon into large 1” slices. Place into sous vide bags and seal in the machine. This will compress the fruit and give it a dense, very juicy texture. Remove from the bags and cut into small dice. Thinly slice the scallions on a bias. Peel the watermelon radish, slice thinly on a mandoline and cut into julienne or desired shape.
To Plate: Arrange four slices of hamachi onto 8 chilled plates. Brush lightly with almond oil and sprinkle with fleur de sel. Garnish as desired with the compressed watermelon, watermelon radish, and scallion. Using the mandoline, shave the fresh shelled almonds on top. Spoon the almond foam around and serve.