How to Use Up Leftover Fish Without Causing a Stink

How to Use Up Leftover Fish Without Causing a Stink
Photo: Nata Bene, Shutterstock

Not all leftovers are on the same level. There are tiers. At the top, you’ve got your pasta sauces, your stews, your chilli — the stuff that actually tastes better after a night in the fridge than it does straight off the stove. Then you have your mid-tier, which is most leftovers: mashed potatoes, steak, roasted vegetables, etc. These things taste just fine when reheated, but may need a little TLC to really shine. Then you have deep-fried things (like French fries), which are not very good unless reheated in the air fryer. And finally, you have fish.

Perhaps this is unfair. Leftover fish can be enjoyable, but there’s an almost PSYOP level of hate toward the concept, thanks to so many co-workers who insist on bringing it to work and heating it up in the communal microwave. This direct heat not only dries out leftover fish filets, it can oxidize the oils, creating the dreaded permeating-fish smell that is the root of most inter-office conflicts. There are, however, alternate courses of action you can take if you find yourself with leftover fish. (No matter how you choose to repurpose it, make sure you do so within a day or two.)

Keep it cold

This is the easiest, safest, lowest-effort option. Toss it with some highly seasoned mayo and lemon juice and eat it on a sandwich, or flake the fish and serve it on top of a salad, grain bowl, or a grain salad (which is just a grain bowl with extra vegetables, I think). Drizzle with a punchy vinaigrette. Eat it.

If you want to “transform” or “reimagine” your leftover fish, you can make a little rillettes (fancy pâté-like spread with added fat). Most rillettes is made by confit-ing the meat in its own fat, but fish lard isn’t a real product, so sour cream or crème fraîche are employed to give it a barely spreadable texture. I’ve shared this recipe for salmon spread before, but just to recap, you will need:

  • 140g leftover fish (salmon is especially delicious)
  • 1/2 large shallot, finely diced
  • 1 teaspoon olive oil
  • 1 teaspoon vermouth
  • 2 tablespoons crème fraîche, sour cream, or labneh
  • 2 tablespoons mayonnaise
  • The juice of 1/4 of a small lemon
  • 1 tablespoon chopped chives
  • 1/4 teaspoon salt

Sauté the shallot in the olive oil over medium heat until translucent. Add the vermouth to the pan and let it reduce for about half a minute. Let the vermouth-enhanced shallots cool, then add them to the salmon, along with the rest of the ingredients. Gently stir everything to incorporate, then chill for an hour in the fridge before serving on your finest water crackers, in little endive cups, or in a really excellent tea sandwich. (Oh, and if you want to take it in a smoky direction, just add a drop or two of our friend liquid smoke. It’s cheating, but it’s the good kind of cheating.)

Heat it indirectly

Perhaps you’re not in the mood for a cold lunch (or supper). That’s fine. You can reheat fish, you just have to do it carefully, gently, and indirectly.

As I mentioned earlier, nuking already cooked fish in the microwave, or placing it in a hot pan, can dry it out and cause the fats to oxidize, creating a terrible, ultra-fishy aroma.

Luckily, there are a few ways you can work around this. First, you’re going to want to decide how you want to eat the fish. I’m really into rice bowls right now, but pasta is another good option, as is a mélange of vegetables. Flake the fish into small pieces — the smaller they are, the more quickly and evenly they will heat. Place the fish in a bowl and set it aside.

Cook your pasta (and sauce), your rice, or your vegetables. You can also prepare a simple pan sauce by reducing white wine with some garlicky browned butter. You just need something hot to toss with the fish. Once your rice, pasta, vegetables, and/or sauce is piping hot, transfer the hot food to the bowl with the fish and toss it all together. The residual heat from the pasta/rice/vegetables/sauce will gently warm the fish, without any oxidized oil smell.

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