In a fish poacher place salmon and add water just to cover. Remove salmon to a plate. To poacher add onion, carrot, celery, fennel, lemon juice, white wine, peppercorns, salt and bring mixture to a boil then reduce to a simmer. Season salmon on both sides with salt and pepper, and add it back to poaching liquid and simmer for approximately 15 minutes or until salmon is cooked through. Remove salmon, cool for a few minutes and carefully remove skin. Chill covered in the refrigerator for at least 1 hour and up to 4 hours before serving with sauce. Sauce: In a small saucepan over medium high heat add vinegar and reduce by half. Add preserves and horseradish and heat thoroughly. Stir in lemon zest and remove from heat. Serve warm with fish.