To the bowl of a food processor or high speed blender, add all ingredients. Pulse a few times, then process on high speed until crema is smooth and creamy.
If crema is too thin, add 1 teaspoon additional sour cream or another 1/2 avocado, then pulse to combine.If crema is too thick, blend in 1 teaspoon of water at a time, until you reach the desired consistency.
Transfer avocado crema to a squeeze bottle or store in a small mason jar with a lid.Keep crema in the fridge and use within 1 week.
Notes
Mexican crema has a thinner consistency with a more bland flavor than sour cream. Also, your sour cream may have a thickener added to it, resulting in a thicker consistency.
For a kick of spicy flavor, add 1/8 teaspoon of cayenne pepper or a couple of dashes of hot sauce to the ingredients.