Line broiler pan with aluminum foil and place broiler pan in the oven
In a small mixing bowl, whisk together sugar, mustard, ginger, pepper, juice, and soy sauce.
Rinse tuna steaks and pat dry with a paper towel. Remove the preheated broiler pan from the oven and lightly coat foil with cooking spray. Place the tuna steaks on the pan. Brush the top side of each steak liberally with the glaze.
Broil (6" from heat) 6 minutes or until fish is lightly browned and opaque.
Remove the pan from the oven, flip the tuna steaks and brush the other side with the glaze.
Return the tuna steaks to the oven and broil another 2-4 minutes, or until fish is done and flakes easily with a fork.