Cut the wild salmon into semi-escalopes of 20 g (12 pieces)
Mix the ingredients in the food processor, pouring in the butter as if making a mayonnaise. Fill the syphon and load with the two cartridges. Place in a bain marie without exceeding 75º.
For the tarragon oil, heat it slightly and then infuse the tarragon and process in a blender.
Sear the wild salmon on the griddle on one side only.
Thinly slice the fennel and crisp up in iced water.
Remove any stalks from the herbs.
Season the salad of anise herbs and fennel with grapefruit juice, grapefruit zest, oil and salt
Place the salad at one end of the plate, the salmon at its side, and finish by saucing with the béarnaise foam and tarragon oil.