This is an all-in-one sauce, adding creaminess and that delicious cilantro flvaour to your whole taco. If you don't want to do this extra step, simply use chopped cilantro and plain yogurt as a garnish. But I like this version because of the beautiful colour of the sauce, and the simplicity of then tossing it in a jar in the fridge, and putting it on top of everything (think salads, grain bowls, pitas).
Add al of the ingredients to a blender or food processor. Pulse until the cilantro is chopped and fully incorporated in to the yogurt, and the sauce takes on a lovely bright green colour. Taste and adjust seasoning. Store in the fridge up to 3 days.