Problem: Low Acid Foods – The trick to canning shelf-stable foods is the acidity. If you have the right amount of acidity, it creates an unpleasant environment for dangerous botulism bacteria to grow. When canning low acid foods such as green chiles, you need to either can them under pressure (using a pressure-canner), or if you use a simple water-bath canning process, add enough acidity to prevent bacteria from growing.
IMPORTANT: Follow the directions carefully and exactly for each recipe. Use the amounts of each vegetable listed in the recipe. Add the amount of vinegar or lemon juice listed. You may decrease the amount of spices if desired. Do not can salsas that do not follow these or other research-tested recipes. These salsas may be frozen or stored in the refrigerator. Do not thicken salsas with flour or cornstarch before canning. After you open a jar to use, you may pour off some of the liquid or thicken with cornstarch.
As you will notice when we dive a little further into these recipes, Mexican food has a stunning range of somewhat special ingredients. From Masa Harina, the essential ingredient of corn over a wide array of chilies either fresh, dried or ground to Mexican oregano and tomatillos. Some of these may at first glance seem foreign and difficult to come by, but fear not we’ll discuss the individual ingredients as we go and they’ll be easier to come by than you think.