Cook oil and curry in small saucepan over medium-low heat, 4 minutes. Add broth. Simmer until reduced to 1/3 cup, 15 minutes. Whisk in sour cream, orange juice, honey, zest, lemon juice and salt if using. Pour dressing into small heatproof pitcher. Chill while preparing salad.
Arrange chicken, asparagus and orange sections on lettuce leaves. Serve with dressing. Makes 4 servings.