Place potato in a Dutch oven; cover with water. Bring to a boil. Reduce heat, and simmer 20 minutes or until tender; drain. Place potato in a large bowl. Add sour cream and remaining ingredients; mash with a potato masher to desired consistency.
These were ok. It was too dry with just 1/4 cup buttermilk, so I ended up adding a whole cup and that made the texture just right. And there's only 120 calories per cup of buttermilk, so it added less than 10 calories more per serving to add the extra 3/4 cup. I think there was too much basil, so if I make it again I'll add more dill and less basil. The potatoes tasted sort of like spaghetti sauce with the amount of basil called for, not very ranch-y. I did like the peel left on the potatoes, gave it some nice texture.