A delicious glaze for salmon. It's not necessary to marinate in advance. This makes a modest amount of sauce/glaze. Should you desire more to serve over rice, increase the amounts but add after removing the fillets from the pan.
Grind together the ginger, chile pepper, garlic and sugar in a mortar and pestle to get a coarse paste. Transfer paste to a bowl and add fish sauce, lime juice, Sriracha and water; mix to combine. Season with salt; set aside. (This may be done in a small food processor bowl or blender.) This sauce will be divided.
Dry with paper toweling and season salmon with salt. Pour over the fillets 4 tablespoons sauce, turning to coat. Set aside the remaining sauce.
Heat oil in a non-stick skillet. When hot, add the salmon fillets and the sauce used for coating; cook over moderate heat. (Don't add more otherwise you will 'boil' the fillets instead of glazing.) Turn fillets over so that both sides are cooked, scooping glaze over top. Continue to cook until it carmelizes, coating the salmon. Remove the fillets then immediately add to the hot pan the reserved sauce mixture, simmering until it becomes golden and thick. Pour over reserved fillets.