This is one of those recipes that came about during the Depression. My Grandma and Mom have been making this for me for as long as I can remember. To this day it it my favorite foods, and I make it by the bowl and eat it a few times a week.
Add just enough tomato juice so your noodles won't stick to the pot.
Add salt and butter, stir until butter is melted.
In a separate bowl mix sour cream with tomato juice by adding a few tablespoons of tomato juice at a time until sour cream and tomato juice mixture is runny and well mixed through (this is done so the sour cream does not curtle when mixed with the hot pasta).
Add mixture and remaining tomato juice to pasta, stir and serve immediately (when left to sit, the pasta will soak up the juice and it will taste slightly different). I like mine best fresh, that's why I make it a bowl at a time. I also never measure anything for this recipe. All amounts can be adjusted to suit your personal preference. These measurements are simply a baseline.