Pat salmon dry and season with salt. Heat a 12-inch nonstick skillet over moderately high heat until hot and sear salmon on flat sides until golden, 2 1/2 to 3 minutes total. Add wine, pepper, gingerroot, and garlic and cook salmon at a bare simmer, turning pieces over once, until just cooked through, 5 to 6 minutes total. Transfer salmon with a slotted spatula to 4 heated plates and keep warm, covered. Cut butter into 3 pieces. Boil cooking liquid until syrupy and reduced to about 1/4 cup. Remove skillet from heat and add butter, stirring until incorporated. Season sauce with salt and pour over salmon.
