Pat the salmon fillets dry with paper towels. Season the flesh with 3/4 teaspoon of the kosher salt.
Juice the lemon half to obtain 1 tablespoon of juice. In a small bowl, combine the lemon juice, honey, soy sauce, and the remaining 1/2 teaspoon kosher salt. Whisk until the honey is completely dissolved.
Mince the garlic cloves.
Heat the olive oil in a large nonstick or cast iron skillet over medium heat until shimmering. Place the salmon fillets skin-side up in the skillet, pressing them down with a spatula to ensure even contact and browning. Cook without moving, gently pressing on the fish periodically, until the bottom is golden-brown, about 5 minutes.
Flip the salmon, cook for an additional 2 minutes, then add the minced garlic and cook until fragrant, about 15 seconds. Pour the prepared sauce over the salmon, continue cooking while spooning the sauce over the fillets until the sauce thickens and reduces by about half, and the salmon is just cooked through, 3 to 4 minutes. The internal temperature should reach 120°F to 130°F for medium-rare or 135°F to 145°F for more well-done.
Garnish with thinly sliced scallions if desired.