In a blender, combine the herbs and water for about 2 minutes. Stop and scrape down the sides if needed. If you need to add a little more water to really get a good puree, add a tablespoon at a time.
Add the salt and blend again.
Add the room temperature butter and blend for 1-2 minutes or until everything is well combined and the butter is a more "whipped texture".
You can serve immediately, but I like to refrigerate for about 30 minutes before serving.
Keeps for up to one week to two weeks in an airtight container in the refrigerator.