1. Combine steak seasoning and tarragon in a small bowl; set aside.
2. Heat a grill pan over medium-high heat. Coat pan with cooking spray. Coat fillets with cooking spray, and rub with seasoning mixture. Add fish to pan. Cook 3 to 4 minutes on each side or until fillets flake easily when tested with a fork.
3. While fish cooks, grate 1 teaspoon rind from lemon; squeeze juice to measure 1 tablespoon. Reserve lemon rind for Country-Style Dijon Cream Sauce.
4. Place 1 fillet on each of 4 serving plates. Drizzle fillets evenly with lemon juice, and top with a dollop of cream sauce.