Don't worry if your recipe calls for sour cream and you don't have any. There are several substitutes you can use that will take the place of sour cream.
What is sour cream?
Sour cream is cream to which the bacteria from lactic acid has been added. The bacteria turns it from sweet to sour.
Baking
When baking, you can substitute 1 cup yoghurt for 1 cup sour cream. Another option is 3/4 cup yoghurt, sour milk or buttermilk plus 1/3 cup melted butter.
Dips
When making dips, you can use 1 cup yoghurt instead of 1 cup sour cream. Drain the yoghurt in a sieve lined in cheesecloth for 30 minutes so it won't be watery.
Cooked Sauces
When making a sauce, substitute 1 cup yoghurt, 1 tbsp flour and 2 tsp water for 1 cup sour cream.
Low Fat
If your goal is to lower the fat content of your dish, you can add 1 cold can of evaporated milk and 1 tsp of lemon juice instead of 1 cup sour cream.