The day before using, cook the fennel any way until soft - sauté, steam or roast it.
Chop cooked fennel finely and chill.
Bring butter to room temp and soften in a bowl by stirring.
Add other ingredients and mix.
Using a piece of wax paper make the butter compound into a long strip and roll into a tube, chill.
Cook salmon over an open flame and top with slices of the chilled compound butter.
Serve with a salad.