Bring the grapefruit, orange and lemon juice to the boil in a pan. Turn down the heat, reduce the liquid to approx. 75 ml, leave to cool. Stir in the oil, season.
Add the salmon to the citrus sauce along with all the other ingredients up to and including the dill, mix. Plate up the tartare with the help of a round cutter, garnish with grapefruit and celery greens.