1Season the halibut with the lemon zest, thyme, and parsley. Cover and refrigerate at least 4 hours or overnight.
3Place the potatoes in a medium pot, cover with cold water (by at least 4 inches), and add 1 tablespoon salt. Bring to a boil, turn down the heat, and simmer gently for about 15 minutes, until the potatoes are tender when pierced. Reserve a cup of the water and strain the potatoes. When the potatoes have cooled, slightly smash them with the heel of your hand.