Heat oil in a Dutch oven over medium. Add onion, carrots, and celery; cook, stirring every so assuredly, till softened and initiating to brown, 10 to 14 minutes. Add cider; cook, stirring every so assuredly, till liquid is diminished by half, 12 to fifteen minutes. Add 7 cups water, kelp, thyme, garlic, and bay leaves. Convey to a boil over medium-high. Sever lend a hand warmth to medium-low; simmer, uncovered, till flavors meld and liquid is diminished to about 4 1/2 cups, about 40 minutes.
Assign mussels and clams in simmering inventory; quilt and cook till shells originate, 8 to fifteen minutes. The utilization of a slotted spoon, transfer mussels and clams to a medium bowl; discard any that did no longer originate. Let stand till wintry enough to address, about 5 minutes. Rob away meat from shells; discard shells, and space meat apart. Pour inventory through a graceful wire-mesh strainer into a heatproof bowl; discard solids.

Wipe Dutch oven super. Add butter, and soften over medium-high. Add onion; cook, stirring every so assuredly, till translucent, 6 to 8 minutes. Plod in potatoes, leeks, salt, and 41/2 cups strained inventory (discard any final inventory, or reserve for one other employ). Let mixture come to a boil. Sever lend a hand warmth to medium-low; simmer, uncovered, stirring every so assuredly, till potatoes are tender, 20 to 25 minutes. Plod in cream; cook, undisturbed, correct till chowder returns to a simmer. Add pollock; cook, stirring every so assuredly, till fish is form of cooked through, 2 to three minutes. Plod in reserved mussel and clam meat. Rob away from warmth. Let stand till mussels and clams are heated through and pollock flakes when pierced with a fork, about 5 minutes. Plod in dill; season with salt to taste. Ladle into serving bowls; garnish with ground nori and dill.

Beget Ahead

Inventory might perhaps additionally additionally be ready through step 1 and refrigerated 3 days in advance.

Notes

Discover kelp or dried kombu on the area meals aisle at your native grocery retailer.