Rinse fish and pat dry. In a small bowl, mix honey, miso, lemon juice, and ginger. Brush fish generously all over with honey mixture. Set pieces slightly apart on a 12- by 15-inch baking sheet.
Broil salmon 3 to 4 inches from heat, turning once with a wide spatula, until opaque but still moist-looking in center of thickest part (cut to test), 7 to 8 minutes total.
Set a piece of fish on each of four plates and mound daikon equally alongside.