1) In a small bowl, mix together mustard, soy sauce, sugar, oil and horseradish until blended well.
2) Spread 1/2 of the marinade over fish using a brush.
3) Cover and marinate the fish for up to 6 hours in refrigerator, if desired.
4) Arrange the fish on grill and cook for 5 minutes.
5) Carefully flip the fish and brush with remaining marinade.
6) Grill the other side until fish flakes off easily.
7) Serve the Savory Salmon Steaks hot over the bed of mixed salad or mashed potato as desired.