Step 1

Season the salmon all over with salt. In a 12-inch nonstick skillet over medium-high, heat the oil until shimmering. Add the mushrooms and cook, stirring occasionally, until the moisture released by the mushrooms has evaporated and the mushrooms are browned, 4 to 6 minutes.

Step 2

Add the garlic, shallots, tarragon sprig and ½ teaspoon salt; cook, stirring often, until the garlic is golden brown, 1 to 2 minutes. Add the wine and cook, stirring occasionally, until reduced by about half, 3 to 5 minutes. Add the broth and bring to a simmer. Place the salmon boned side down in the pan, reduce to low and cook at a very gentle simmer, uncovered, for 5 minutes. Flip the fillets and cook until the thickest parts reach 120°F or are slightly translucent when cut into, 2 to 3 minutes.

Step 3

Remove the pan from the heat. Using a wide metal spatula, transfer the salmon to wide, shallow serving bowls. Bring the broth to a simmer over medium-high, then add the artichokes and butter; cook, stirring, until the artichokes are heated through and the butter is emulsified into the sauce, about 1 minute. Off heat, taste and season with salt. Remove and discard the tarragon sprig, then spoon the mixture over and around the salmon and sprinkle with the chopped tarragon.