Remove the pulp of the preserved lemon and finely dice the skin.
Peel and grate the ginger. Juice the lemon.
Finely dice the tomato. Finely chop the chives.
Mix the mackerel rillettes with the ginger, preserved lemon, diced tomato, chives and lemon juice. Season if necessary.
Place in a jar and store in the refrigerator.
Serve on toasted bread.
To liven up this dish, add a few pinches of Espelette pepper.