Possible substitutes for sour cream include yogurt, butter, buttermilk, sour milk or evaporated milk. The best substitute for sour cream depends on the recipe and the type of food being made.
For baking, 1 cup of sour cream can be substituted for 1 cup of yogurt mixed with 1 teaspoon of baking soda, 3/4 cup of sour milk mixed with 1/3 cup of butter or 3/4 cup of sour milk mixed with 1/3 cup of butter.
For cooked sauces, 1 cup of sour cream can be substituted for 1 cup of evaporated milk mixed with 1 tablespoon of vinegar or 1 cup of yogurt mixed with 1 tablespoon of flour and 2 tablespoons of water. To use yogurt as a substitute, first strain it through a cheesecloth for thirty minutes to allow it to thicken.