Boil 4 husked and rinsed tomatillos in a pot of water, 5 minutes. Puree 1/2 cup chopped cilantro, 1/2 cup chopped white onion, 1 chopped jalapeno and a splash of the tomatillo cooking water in a blender. Drain the tomatillos, add to the blender and pulse. Add 2 chopped avocados and 1 teaspoon kosher salt and pulse. Season with more salt to taste.