Rinse fish; pat dry with paper towels. Place fish in a plastic bag set in a deep bowl; set aside. Combine orange peel, orange juice, olive oil, and the 2 teaspoons tarragon; pour over fish, turning to coat. Seal bag; let stand at room temperature for 20 minutes.
Meanwhile, preheat oven to 425 degee F. In a small dish combine mustard, melted margarine or butter, and honey; set aside. In another dish combine bread crumbs, pecans, parsley, and the remaining 2 teaspoons tarragon. Remove salmon from marinade; discard marinade.
Place fish, skin side down, on greased shallow baking pan. Brush with mustard mixture; sprinkle with crumb mixture, pressing crumbs gently to coat. Bake, uncovered, for 12 to 16 minutes or until fish just flakes easily with a fork. If desired, sprinkle with additional tarragon and parsley. Garnish with lemon slices. Makes 4 servings.