Combine soy sauce, mirin, honey, water, ginger, and cilantro in a small saucepan over high heat. Once it boils, turn heat to low and simmer for 2 minutes. Remove from heat and let cool. Once sauce is cool pour into a large bowl or plastic bag and add the salmon., Marinate in the fridge for at least an hour, up to overnight.
When ready preheat your broiler.
Put salmon on a heavy baking sheet with whatever sauce adheres to it and broiluntil cooked to your liking, about 7-8 minutes is good for me. While salmon is cooking, strain extra marinade into a clean saucepan, bring to a boil, and let reduce.
Serve salmon drizzled with some of the extra sauce and a sprinkle of chives.