Stir together creme fraiche, horseradish and vinegar. Refrigerate until ready to serve.
If needed, fillet fish; remove fine bones using tweezers. Place fillets on baking sheet with sides, skin side down. Mix together salt, sugar, apple cider, orange, lemon, and lime zests. Spread over prepared fish fillets. Cover with plastic wrap and refrigerate for 1 hour.
* Grilling on a gas grill: Use a well oiled fish basket or grill tray. Heat grill to high (with grill tray inside); for grill marks, place fillets skin side up on grill tray, turn grill heat down to low/medium-low and cook about 3 minutes. Carefully turn fillets over, skin side down, and continue to grill (2-3 minutes longer) until done.
*Lightly smoked grilled fillet: Heat grill to low/medium-low heat. Spread approximately ½-¾ cup dry wood chips in a metal or foil 9x13 pan, cover loosely with foil and poke 3-4 holes in top. Remove grill grate using tongs, place pan directly over flame diffuser, replace grate and close lid. When heaviest of smoke has subsided, place fillets skin side down on a grill tray and close lid. Cook 5-8 minutes or until done.