In a 1- to 2-quart pan, mix soy sauce, honey, and garlic. Stir often over medium-high heat until glaze is reduced by about a third, 7 to 10 minutes.
Pour 3 tablespoons glaze into a small bowl and reserve. Pour remainder into a shallow 2- to 3-quart baking dish. Set salmon pieces in dish, skin side up; let stand 15 minutes. Turn salmon pieces over.
Bake in a 450° oven until salmon has turned opaque at the edges but is still translucent in the center (cut to test), 15 to 20 minutes. Remove from oven.
Increase oven heat to broil. Brush salmon evenly with about half the reserved glaze and sprinkle evenly with sesame seeds. Broil 6 inches from heat until sesame seeds are toasted and salmon is opaque but still moist-looking in center of thickest part (cut to test), 2 to 3 minutes.
Drizzle salmon with remaining reserved glaze. Use a wide spatula to transfer pieces to plates.