What is added to the Crunchy Taco to make it a Crunchy Taco Supreme?

The addition that transforms a regular Crunchy Taco into a Crunchy Taco Supreme is sour cream. This upgrade enhances the texture and flavor profile of the taco, providing a creamy contrast to the seasoned beef, lettuce, and cheese already present in the original Crunchy Taco. The sour cream not only adds richness but also balances the spices in the other ingredients, making it a more indulgent option. While lettuce is already included in both variations, and nacho cheese could complement the taco but does not define the Supreme version, it is the sour cream that specifically distinguishes the Crunchy Taco Supreme from its base counterpart. Tortilla chips, while a tasty Taco Bell offering, are not included in either taco and do not contribute to the Supreme classification.