Peel and finely dice the shallots. Place in a sieve and pour over boiling water.
Wash the fennel. Peel the kohlrabi. Cut the fennel and kohlrabi into cubes.
Wash the watercress and shake dry. Tear or cut into bite-size pieces.
Sprinkle the salmon with pepper.
Heat half the oil in a pan and fry the salmon for 3-4 minutes on each side. Sprinkle with some salt.
Mix the vinegar with the remaining oil, mustard and honey. Mix with the kohlrabi, fennel, shallots and watercress, and serve with the salmon steaks.