Before you cook, I like to pat my cod dry and season both sides with salt and pepper—this ensures the seasonings stick and the fish sears properly. Lightly dust one side of each filet with flour; this gives the fish a delicate crust and helps thicken the sauce later.
Heat half the butter in a large skillet over medium‑high heat. Once it stops foaming, add the cod filets with the floured side down. Let them cook undisturbed so they brown slightly, about 3 minutes. This step seals in moisture and flavor.
After removing the fish, toss in your lemon slices, shallots, and capers so they soak up the buttery goodness left in the pan. This mix becomes the aromatic base for your sauce.
Pour in the white wine and scrape up those tasty browned bits from the skillet. Then add the chicken broth, parsley, and lemon juice. Let it simmer for a few minutes until everything melds into a tangy, silky sauce.
Gently return the cod to the pan and let it cook in the sauce until it reaches 145°F inside. I always check with a thermometer to avoid overcooking. If you want a thicker sauce, mix the remaining butter with a bit of flour or make a slurry to finish it off.