As we learned with recipes for beef, lamb, pork, and poultry, cooking en cocotte — cooking a protein in a covered pot with little to no liquid —concentrates flavor.
To ensure uniform pieces of fish that cook at the same rate, we prefer to buy a whole center-cut fillet and cut it into evenly sized individual fillets ourselves. If buying individual fillets, make sure they are the same size and thickness.
If the fillets are thicker or thinner than 1½ inches, you may need to adjust the cooking time slightly. If you can find only skin-on fillets, remove the skin before cooking or the sauce will be greasy.
Start to finish: 50 minutes
1 (1½ to 2 pound) skinless salmon fillet, about 1½ inches at thickest part
Salt and pepper
2 tablespoons extra-virgin olive oil
2 leeks, white and light green parts only, halved lengthwise, sliced thin and washed thoroughly
2 sprigs fresh thyme
2 garlic cloves, minced
½ cup dry white wine
2 tablespoons unsalted butter, cut into 2 pieces
Adjust oven rack to lowest position and heat oven to 250 F. Trim any whitish fat from belly of fillet, then cut fish into 4 equal pieces. Pat salmon dry with paper towels and season with salt and pepper.
Heat oil in Dutch oven over medium-low heat until shimmering. Add leeks, thyme, and pinch salt, cover, and cook until softened, 8 to 10 minutes. Stir in garlic and cook until fragrant, about 30 seconds. Remove pot from heat.
Lay salmon, skinned side down, on top of leeks. Place large piece of aluminum foil over pot and cover tightly with lid; transfer pot to oven. Cook until salmon is opaque and flakes apart when gently prodded with paring knife, 25 to 30 minutes.
Transfer fish to serving platter and tent with foil. Stir wine into leeks in pot and simmer over medium-high heat until slightly thickened, about 2 minutes. Off heat, whisk in butter and season with salt and pepper to taste. Spoon sauce over salmon and serve.
Salmon en Cocotte with Celery and Orange
Add 2 thinly sliced celery ribs and 1 teaspoon minced orange zest along with garlic in step 2. Substitute ½ cup orange juice for wine, and add 1 orange, peeled and segmented, when thickening sauce.