In a saucepan, combine the soy sauce, honey and vinegar. Bring to a boil and simmer for 1 minute. Stir in the garlic.
Season the salmon on both sides with salt. Preheat a large, heavy skillet over medium-high heat. Add the oil, swirling to coat, then add the salmon, skin side down, and cook, undisturbed, until the skin is very crisp, about 6 minutes. Turn and cook until opaque at the thickest part, 1 to 3 minutes.
Drizzle serving plates with the sauce, place the salmon, skin side up, on top and sprinkle with the scallion.