Pat halibut fillets completely dry with paper towels and let sit at room temperature for 15 minutes. Season all sides generously with kosher salt and black pepper.

Heat a large stainless steel or cast-iron skillet over medium-high heat. Add the oil and heat until it shimmers.

Place the halibut fillets presentation-side down in the hot pan. Sear undisturbed for 4-5 minutes, until a deep golden-brown crust forms.

Flip the fillets carefully with a fish spatula. Cook for another 2-4 minutes, or until the internal temperature reaches 130-135°F. Remove fish to a plate and tent with foil.

Reduce heat to medium-low. Add the minced garlic to the pan and cook for 30 seconds until fragrant.

Deglaze the pan with the white wine, scraping up any browned bits from the bottom. Simmer until the wine has reduced by half, about 1-2 minutes.

Remove the pan from the heat. Whisk in the cold butter cubes, one at a time, until the sauce is creamy and emulsified.

Stir in the fresh lemon juice and chopped parsley. Pour the sauce over the halibut fillets and serve immediately.