To raise the temperature of a cold liquid gradually by slow
stirring in a hot liquid. Example: when making Beef
Stroganoff, the sour cream is added at the end of cooking.
If you just stirred in the sour cream to the hot liquid the
sour cream would break and look curdled. Place the sour
cream in a 1 qt bowl, ladle a small amount of hot gravy into
sour cream, stirring well. Repeat this process until the
sour cream mixture is hot to the touch. Add the sour cram
mixture to the stroganoff, stir well, reduce heat.