In a large skillet, bring 4 cups water to a boil. Add asparagus; cover and cook for 2 to 2-1/2 minutes. Drain and immediately place asparagus in ice water. Drain and pat dry.
In a small saucepan, combine the sour cream, mayonnaise, lemon juice, mustard, basil, dill, pepper, garlic powder and salt. Cook and stir over low heat just until heated through. Serve with asparagus. Yield: 12 servings.