If I bought buttermilk, which I don’t, I would waste more of it than I could ever use. So I use this handy little trick anytime I need buttermilk for a recipe. Works like a charm in 3-5 minutes!
For each cup of buttermilk required, place one tablespoon white vinegar in a measuring cup, then add enough milk to make one cup total liquid. Increase or decrease proportionately for the amount needed, keeping in mind the following conversions:
3 teaspoons = 1 Tablespoon
1 1/2 teaspoons = 1/2 Tablespoon
So, 1/3 cup of buttermilk required will use 1 teaspoon vinegar and the rest of the 1/3 c full of milk. (You’ve got this, right?)
Let it sit for five minutes (I usually hover around three minutes, because I don’t realize I need it until the last second!)