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Fork cutting into flaky piece of butter-poached cod

Butter-Poached Icelandic Cod

20 min
10 min

Brought to you by Ari from Well Seasoned Studio.

Butter-poached cod is a foolproof way to get tender, succulent fish every single time. The cod cooks slowly in clarified butter with tarragon, garlic, and chilies, leaving it moist and flaky with a subtle heat. Serve with a simple homemade tarragon aioli that takes the whole dish over the top!


For the poached fish:

2 lbs butter unsalted

1 ½ lb cod

3 sprigs fresh tarragon

2 cloves garlic smashed

1 red or green chili thinly sliced, optional

1 tsp Kosher salt

¼ tsp freshly ground black pepper

Chives finely chopped, for serving

Sea salt for serving


For the tarragon aioli:

1 large egg

1 clove garlic minced

4 tsp fresh lemon juice

½ cup canola oil

½ cup extra virgin olive oil

½ tsp Kosher salt

⅛ tsp freshly ground black pepper

2 Tbsp fresh tarragon finely chopped


  1. To make clarified butter, place butter in a large skillet or sauce pan over low heat until melted. Allow to cook until the milk solids float to the top. Once the butter stops bubbling, use a spoon to skim the foam off the top of the butter, then discard. What remains is clarified butter!
  2. Add tarragon, garlic and sliced chili (if using) to clarified butter, then warm over medium heat. Make sure the skillet is large enough to fit all pieces of cod in an even layer. Cut cod into 3 or 4 roughly equal-sized pieces. Season cod on both sides with salt and pepper. Add the cod to the warm butter, then cover and poach until cooked through, about 6–10 minutes. Thinner pieces of cod (the tail) will finish cooking before the tenderloin (thicker piece.) You can carefully remove the cooked cod with a large spatula or spoon and transfer to a plate or serving platter while the remaining pieces cook through. Meanwhile, make the tarragon aioli.
  3. For the tarragon aioli, place the egg, minced garlic and lemon juice into the bowl of a food processor fitted with blade attachment. With the motor running, slowly stream in the canola oil until the sauce has thickened up, about 30 seconds to a minute. Scrape down the sides as needed, process once more, then transfer to a bowl.
  4. Slowly stream in the extra virgin olive oil while whisking constantly until incorporated and thick.
  5. Add chopped tarragon, salt and pepper, and mix to combine. Serve over poached cod. Garnish with chives, a tiny sprinkle of sea salt and some freshly cracked black pepper.


When making clarified butter, you will lose about 25% of the volume that you began with. It’s easy to scale up or scale down the quantity you make as needed. Clarified butter can be used in any recipe that calls for butter, and is especially delicious served alongside seafood, such as lobster or crab, mixed in with scrambled eggs or with any vegetable side dish.

When stored properly in a sealed airtight container, clarified butter will keep for up to 6 months in a refrigerator.

To make aioli with an immersion blender: place egg, garlic and lemon juice in a glass or cup large enough to fit the head of the immersion blender. Add canola oil, then place the immersion blender in and turn on. Process until aioli forms, lifting and tilting the head of the blender slightly so that the sauce is well incorporated. Transfer to a bowl, then continue with instructions to stream in, whisk olive oil and then add tarragon.