Put the oil in a small stainless-steel, enameled, or nonstick roasting pan and heat in the oven for 5 minutes. Season the fish with 1/2 teaspoon salt and 1/4 teaspoon pepper.
Put the fish in the hot pan; cook in the oven until just done, about 8 minutes.
Remove the fish from the pan and transfer to paper towels to drain.
Pour off any oil remaining in the pan.
Put the pan over moderate heat and add the wine and the chopped scallion bulbs. Bring to a boil, scraping the bottom of the pan to dislodge any brown bits. Cook until the wine is reduced to approximately 3 tablespoons, 1 to 2 minutes.
Reduce the heat to low and whisk in the butter. Season the sauce with a pinch each of salt and pepper.
Put the fish on plates, browned-side up.
Sprinkle the scallion greens over the top. Spoon the sauce around the fish.
Fish Alternatives: Firm tuna steaks would taste delicious with the red-wine sauce. Milder fish steaks to use include halibut and cod.
Variation: Salmon with Horseradish Cream Sauce: Roast the fish as described in step 1 but serve the roasted salmon with the horseradish cream from Crab Cakes with Horseradish Cream, (step 1), instead of with the red-wine sauce.
Wine Recommendation: Pinot noir is a classic wine match with salmon. Look for a recent vintage from either California or Oregon and chill it for fifteen minutes before serving.
