Light Tomato Sauce

This is a good sauce in its own right, but it is also one of those basic formulas that can be transformed in the handling. A good caldillo de tomate is the basis of many a Mexican sauce and provides the flavor basis for countless soups and other dishes. It is a traditional sauce for chiles rellenos (for example, the vegetarian version). I like to use the enriching technique of sautéing the mixture in one or two tablespoons of lard or but