Plokkfiskur with Rye Bread

I want a fish dinner that is not a fillet-with-sides, and plokkfiskur is the opposite: the fish disappears into something closer to a savory mash, which is exactly the texture a cautious eater will accept when a whole piece of fish gets pushed around the plate. It is also a lesson in Nordic frugality, a dish that exists because nothing in an Icelandic kitchen was wasted, and I like the idea of cooking something whose whole point is making the most of a cheap catch. Cod, potatoes, onion, milk, flour and butter are all things I can buy at any grocery store. The question is whether the rye bread, which is half the experience, can be found or faked.

• Cod or haddock: Both are traditional. Frozen cod fillets, thawed, are perfectly suited since the fish is poached and flaked anyway. Pollock is a cheaper stand-in.
• Dark rye bread: Real rúgbrauð is dense, moist and sweet. The nearest supermarket match is German-style whole-grain rye or pumpernickel, sold sliced in cellophane packs (Mestemacher is common, in the bread aisle or the international section). Trader Joe's and Aldi often carry a version. Not deli rye, which is light and seeded.
• Whole milk and butter: The sauce is a simple béchamel; low-fat milk makes it thin and gray-tasting.
• Curry powder (optional): A small pinch is a common modern Icelandic touch. It is not required and I'd leave it out the first time.

1. Peel the potatoes and cut them into 1-inch chunks. Put them in a pot of cold salted water.
2. Finely dice the onion.
3. Cut the fish into 3 or 4 large pieces and check for bones. Season lightly with salt.
4. Measure the milk, flour and butter so the sauce comes together without stopping.
5. If finishing in the oven, heat it to 400°F and butter a baking dish.

1. Bring the potatoes to a boil and cook 15–18 minutes until completely tender. Drain, return to the pot and break them up roughly with a masher or fork; you want chunks and crumbs, not a smooth purée.
2. While the potatoes cook, poach the fish: in the large saucepan, bring 2 cups water with 1 teaspoon salt and the bay leaves to a bare simmer. Lower in the fish and poach 5–7 minutes, until it flakes. Lift the fish out onto a plate and discard the poaching water (or keep 1/2 cup in case the sauce needs loosening). Flake the fish into large pieces with a fork, discarding skin if any.
3. Wipe the saucepan dry. Melt the butter over medium heat and cook the onion with a pinch of salt for 6–8 minutes until soft and translucent but not browned.
4. Sprinkle the flour over the onion and stir for a minute. Pour in the milk gradually, whisking, and simmer 3–4 minutes until the sauce thickens to the consistency of heavy cream. Season with 1/2 teaspoon salt, a pinch of white pepper and the curry powder if using.
5. Fold in the potatoes, then the fish, gently so the fish stays in flakes. Taste; it usually wants more salt than you expect. If it looks stiff, loosen with a splash of poaching water or milk.
6. Serve straight from the pot, or spread into the baking dish, scatter the cheese over and bake 10–12 minutes until the top is golden at the edges.

Spoon plokkfiskur into shallow bowls with chopped chives on top and pass thick slices of rye bread with a dish of cold butter; the bread is used as a spoon and a sponge. Black pepper goes on at the table. There is nothing in this dish a child needs protected from, so every bowl is the same, which is a relief. Leftovers are, by Icelandic tradition, the point: refrigerate up to three days and reheat gently with a splash of milk, or press cold leftovers into patties and fry them in butter.