Add about 2 inches of water to the bottom of the steam pot and bring to a boil over medium-high heat.
If needed, cut the fish into two filets. Season (to taste) with garlic salt, pepper, and Old Bay. Place fish into the steamer basket. When the water in the pot is boiling, reduce the heat to medium and place the steamer basket in place, cover with lid.
1 pound Chilean sea bass
Steam fish for 8-10 minutes.
Meanwhile, while the fish is steaming, make the sauce. To a medium saucepan, add all the sauce ingredients and bring to a boil. Reduce the heat to medium and cook until the fish is done. Sauce will be slightly thickened and have a brothy consistency.
2 Tablespoons butter, 1/4 cup chopped shallots, 1 Tablespoon fresh lemon juice, 1/4 teaspoon Old Bay seasoning, 1/8 teaspoon black pepper, 1/4 teaspoon garlic salt, 1/2 cup dry white wine, 1 teaspoon onion powder, 1 teaspoon chopped rosemary leaves
Chilean sea bass should reach an internal temperature of 140F degrees (60C) registered on an instant-read thermometer inserted into the thickest portion of the fish.
When choosing Chilean sea bass, opt for the center cut. The tail end of the fish will be flakier but also bonier. The center-cut portions are thick and have a buttery consistency.
We use dry white wine in the sauce for this recipe. You can substitute with chicken stock if you prefer.