Over medium heat, melt brown sugar with honey and butter. Remove from heat and whisk in mustard, soy sauce, olive oil and ginger. Allow to cool. Place salmon, skin side down, on a large sheet of aluminum foil to leave a border of ¼ to ½ inch around edge of salmon. Coat flesh of salmon with brown sugar mixture.

Grill salmon indirectly over medium heat until edges begin to brown and inside is opaque, 25 to 30 minutes. The internal temperature should be about 125 degrees. Using a large baking sheet, carefully transfer the salmon with foil to a cutting board. Cut salmon crosswise into 6 to 8 pieces, but do not cut through skin. Slide a spatula between skin and flesh and remove salmon pieces to a serving platter or individual plates. Serve immediately.