My favorite substitute for buttermilk is a mixture of plain (unsweetened, unflavored) yogurt and water. Usually a mixture of equal parts yogurt and water is ideal. However, you may need a bit more water if the yogurt is very thick or a bit less if the yogurt is thin. For the best results, use yogurt that does not contain any extra thickeners, such as gums or gelatin.

An easy substitute for buttermilk is to mix either lemon juice or a white vinegar with milk. The ratio is 1 Tbsp. juice/vinegar to 1 Cup of milk. Mix them together and let it sit for about 5 minutes. The milk will curdle and voila! you have a buttermilk substitute.

You can add 1-2 tblspoons of lemon juice to sour and slightly curdle the milk. Let stand 20 mins and it is ready. Works best with whole milk.

Have you tried souring milk? All you need is 1 cup of milk and 1 tablespoon of lemon juice. Place the lemon juice in a liquid measuring cup and then add the one cup of milk.

If you are really in a pinch for buttermilk and have no milk or lemon juice, you can use one cup of plain yogurt. This will yield the same result as using buttermilk.