Dump all ingredients, except for herbs, in a wide-mouth mason jar and blend with an immersion blender for about one minute. Start the blender at the bottom of your jar, working your way up to the top when you start to see it thickening up. Incorporate herbs during the last 15 seconds (otherwise it will turn green). Store in the fridge for up to one week.
Note: If your ranch doesn't thicken, it probably didn't emulsify properly. Just add another egg and blend again.