Combine all of the ingredients in a food processor.
Pulse until smooth and use to top your favorite Mexican dishes.
If you don't have a food processor, you can make this crema by hand. Be sure to chop the cilantro as finely as you can so you don't have any chunks and then really well combine everything in a bowl with a spoon or whisk.
So much of the flavor comes from the lime and cilantro, so use the freshest you can.
To make this crema vegan, swap the sour cream for a dairy-free variety.