Step 1

Measure 1 tablespoon of fresh lemon juice or white vinegar into a 2 cup glass measuring cup.

Step 2

Then, add the whole milk, pouring until the total amount of liquid (the milk plus the lemon juice or vinegar) equals one cup. The amount of milk added will be slightly less than 1 cup of whole milk, or a "scant" one cup (specifically, it will be 1 tablespoon less than 1 cup).

Step 3

Next, let the lemon juice or white vinegar and whole milk mixture sit for 10 minutes at room temperature. The mixture should look curdled.

Step 4

Stir the mixture and now you have homemade buttermilk for your buttermilk substitute! Use it 1:1 with whatever recipe you have that calls for buttermilk.

Step 5

Alternatively, if you don't have fresh milk, you can combine 1/3 cup powdered milk + 1 cup water.

Step 6

Then, add 1 tablespoon white vinegar.

Step 7

Let sit for 10 minutes before using.