From Cook's Illustrated, here are their notes: Butter basting, a technique that involves repeatedly spooning sizzling butter over food as it cooks, is great for mild, lean, flaky fish such as cod, haddock, or snapper. The butter helps cook the top of the fillet as the skillet heats the bottom, allowing you to flip the fish only once and early in the cooking process—before the flesh has become too fragile—so it stays intact. Throughout the process, the nutty, aromatic butter, which we enhanced with thyme sprigs and crushed garlic cloves, bathed the mild fish in savory flavor. We alternated basting with direct-heat cooking on the burner, taking the temperature of the fish so we knew exactly when the fillets were done.
Ingredients
2 (6 ounces) skinless cod fillets, about 1 inch thick (red snapper or haddock)
1/2 teaspoon kosher salt
1/8 teaspoon pepper
1 tablespoon vegetable oil
3 tablespoons unsalted butter, cut into ½-inch cubes
2 garlic cloves, crushed and peeled
4 sprigs fresh thyme
Lemon wedges
Instructions
1. Pat all sides of fillets dry with paper towels. Sprinkle on all sides with salt and pepper. Heat oil in 12-inch nonstick or carbon-steel skillet over medium-high heat until just smoking. Reduce heat to medium and place fillets skinned side down in skillet. Gently press on each fillet with spatula for 5 seconds to ensure good contact with skillet. Cook fillets, without moving them, until underside is light golden brown, 4 to 5 minutes.
2. Using 2 spatulas, gently flip fillets. Cook for 1 minute. Scatter butter around fillets. When butter is melted, tilt skillet slightly toward you so butter pools at front of skillet. Using large spoon, scoop up melted butter and pour over fillets repeatedly for 15 seconds. Place skillet flat on burner and continue to cook 30 seconds longer. Tilt skillet and baste for 15 seconds. Place skillet flat on burner and take temperature of thickest part of each fillet. Continue to alternate basting and cooking until fillets register 130 degrees. Add garlic and thyme sprigs to skillet at 12 o'clock position (butter will spatter). When spattering has subsided, continue basting and cooking until fillets register 140 degrees at thickest point. (Total cooking time will range from 8 to 10 minutes.)
3. Transfer fillets to individual plates. Discard garlic. Top each fillet with thyme sprigs, pour butter over fillets, and serve with lemon wedges.