Prep the salmon: Pat the salmon dry on all sides with paper towels. Season with salt and pepper to taste. Set aside.
Make the glaze: Adjust the oven rack to the middle position and preheat the broiler. In a small bowl, whisk together the garlic, brown sugar, bourbon, soy sauce, and green onions.
Simmer the glaze: Add the butter and oil to a large oven-safe skillet over medium-high heat. Once the butter melts, whisk in the bourbon mixture. Bring to a boil and cook, whisking constantly, for 1 to 2 minutes, until glossy and thick enough to coat a spoon.
Sear and baste: Add the salmon, skin side down if using salmon with skin. Cook for 3 minutes, spooning the glaze over the fillets every 30 seconds or so.
Broil: Transfer the skillet to the middle rack under the broiler. Broil for 5 to 6 minutes, basting once about halfway through, until the top is caramelized and the fish flakes easily with a fork.