Heat oil in a large skillet over medium-high heat. Add halibut steaks and sear until nicely browned, 2 to 3 minutes per side. Transfer to a plate.

Pour wine into the pan and bring to a boil while scraping the browned bits of food off the bottom of the pan with a wooden spoon. Cook until wine is almost completely gone, then stir in garlic, butter, and capers. Season with salt and pepper, then simmer for about 1 minute to blend the flavors.

Return halibut steaks to the pan. Spoon sauce over steaks to coat; cook until fish flakes easily with a fork, 2 to 3 more minutes.

To serve, cut steaks in half and pour pan sauce over top.