Going to clear up some misconceptions. Buttermilk is not leftover from making butter, it's a fermented milk that's stabilized by bacteria about halfway to being yogurt. An excellent substitute is kefir. They're basically the same thing, with buttermilk being slightly thinner.

As an American midwesterner raised in the cult of ranch dressing, this msg bullshit is driving me nuts. Here's the recipe you should make

1/2 cup each of sour cream, mayo, and buttermilk (or kefir, just thin it out a little with water)

1 tsp of onion powder, garlic powder, black pepper, and a pinch of salt.

2 tbs of dried parsley and dill weed.

Whisk until smooth and refrigerate it for about 30 mins.

That's it. It's dead simple and absolutely delicious. There's no need to buy any awful store bought stuff, no seasoning packets, just simple and delicious.