Place the ginger, lemongrass, lime juice, honey, fish sauce, and garlic in a bowl and mix. If you want to make the marinade smoother, you can use a blender or a food processor.
Pour the marinade into a 9x13 baking pan and place the salmon fillet in the pan, turning to coat them well with the marinade. Refrigerate for 30 minutes.
Preheat the oven to 400 F. Line a rimmed baking sheet with parchment paper and spray with nonstick cooking spray. (The parchment paper is optional, but very helpful during clean up!)
Roast the salmon for 10 minutes, or until it is cooked to your liking, remembering that it will continue to cook a bit after it is removed from the oven. Serve hot, with cilantro if desired.
Notes
You can marinate the salmon for up to 2 hours, but longer than that might alter the texture of the fish because of the acidity of the lime juice, making it a bit soft.