Drain fruit salad, reserving 3/4 cup juice.
Combine dry gelatin mix and lime zest in medium bowl. Add boiling water; stir 2 min. until gelatin is completely dissolved. Stir in lime juice and reserved fruit salad juice.
Pour 1-1/4 cups gelatin mixture into 8x4-inch loaf pan sprayed with cooking spray. Refrigerate 1 hour or until gelatin is set but not firm.
Whisk sour cream into remaining gelatin mixture until blended; stir in fruit salad. Spoon over gelatin layer in pan.
Refrigerate 4 hours or until firm. Unmold before serving.