I've got a recipe that calls for some buttermilk, but none on-hand. Is there some way I could use some common ingredient(s) as a substitute?
There are a few possibilities:
I have used the first two with success.
Source: Cook's Thesaurus
I've seen both milk + white vinegar or milk + lemon juice mentioned as substitutes. I've only tried the former, and that worked great. I've used a ratio of 1 cup milk to 1 tablespoon of vinegar.
You can use the aforementioned substitutions for buttermilk but keep in mind that they will produce a slightly different flavor due to the types of acids and their flavor profiles:
-Buttermilk = lactic acid
-Lemon juice = citric acid
-Vinegar = acetic acid
Chemically they will work the same however.
Sour cream or yogurt thinned with milk to the consistency of buttermilk will probably give you the closest substitution in flavor.