Just like the Mexican Restaurants around here. I like my green sauce creamy, the tomatillos in this recipe keep the avocado from going brown for a couple days in the fridge. It doesn't usually last that long!
Remove husks and stems from tomatillos. Place whole tomatillos in a sauce pan, cover with water and bring to a boil. Boil 5 minutes or until easily pierced with a fork. Drain the water and allow to cool.
Place tomatillos, onion, cilantro, jalapeno, and salt in a food processor or blender. Blend until smooth.
Stir in sour cream and avocado and blend again until smooth.