In a small bowl, combine cornstarch, butter and Worcestershire sauce until smooth. Stir in the honey, mustard and pepper.
Place each salmon fillet on a double thickness of heavy-duty foil (about 18x12-in.). Drizzle with honey mixture and sprinkle with walnuts. Place asparagus around salmon. Fold foil around salmon and seal tightly. Grill, covered, over medium heat for 15-20 minutes or until fish flakes easily with a fork.