Low Calorie Apple Cider Salad
["1 envelope unflavored gelatin", "2 c. unsweetened apple cider, divided", "1 Tbsp. plus 1 tsp. lemon juice", "2 medium apples, finely chopped (unpeeled)", "1/2 c. finely chopped celery", "vegetable cooking spray", "lettuce leaves"]
["Combine gelatin and 1/2 cup apple cider in a small, heavy saucepan; cook over low heat, stirring constantly until gelatin dissolves.", "Stir in remaining apple cider and lemon juice.", "Chill until the consistency of unbeaten egg white.", "Fold in apple and celery."]
["unflavored gelatin", "apple cider", "lemon juice", "apples", "celery", "vegetable cooking spray", "lettuce leaves"]