recipes from central Mexico call for cream. It should be slightly sour, liek the creme fraiche of France. I suggest that you make your own, which is far more satisfactory that using the commercial brands.

Put the cream and buttermilk into a glass jar and mix them well together.

Cover with plastic wrap and set the mixture aside in a warm place, but not too warm (a strong pilot light is too warm; the cream will taste "cooked" and a skin will form) until it is set, about 6 hours. Put the crem into the refrigerator overnight; it will thicken and become more solid.

Some creams will sour more quickly, and some become thicker than others. The milk experts inform me that these are uncontrollable factors depending on the culture of the buttermilk, the amount of light and heat to which the cream was exposed before it was used, and even the bateria in one's own kitchen.

For Thin Sour Cream you can substitute light for heavy cream.