Place the halibut in a single layer in a baking dish.
In a small bowl, stir together the orange peel, orange juice, lime or lemon juice, salad dressing and mustard.
Pour over the halibut.
Cover the baking dish with plastic wrap and marinate in the refrigerator for 1 hour, turning the halibut over after 30 minutes.
Spray the rack of a broiling pan with no-stick spray.
Drain the halibut, reserving the marinade.
Place the halibut on the rack and brush with the reserved marinade.
Broil 3" to 4" from the heat for 5 minutes.
Turn the halibut over and brush again with the marinade.
Broil for 4 to 7 minutes more or until the fish flakes easily when tested with a fork and is opaque all the way through.