Got fresh salsa ... in January? It's not as hard to store as you might think.
Assemble your equipment. Because salsa is a high-acid product, it does not require processing in a pressure cooker. However, you will need a large pot that allows the jars to be completely submerged in water (water bath).
Bottles can be used over and over again, as can rings, but lids must be new to seal properly. Be sure bottles are clean before you begin (a dishwasher does the trick and will keep them warm).
Assemble your ingredients. Salsa is primarily made from tomatoes, onions, garlic, peppers, spices and vinegar--allowing a great deal of flexibility to suit individual tastes. There are hundreds of recipes available online; we'll focus on the basics of how it all goes together. For a mild salsa, banana or Anaheim peppers give great flavor without too much burn; jalapenos or habanero peppers, on the other hand, tend to be hot.
Blanch tomatoes. Put clean tomatoes in boiling water for about a minute, or until the skin begins to split. After removing the tomatoes from the water with a slotted spoon, put them in a bowl or sink of cold water to cool the tomato to the point where you can easily slip the skins off. Then either dice by hand, or chop with a food processor--be careful not to puree it.
Chop onions, cilantro, fresh herbs, garlic and other ingredients either by hand or via the food processor until they reach the size you want. Keep in mind they will soften as they cook and process. If you like a chunky salsa, keep your chopping to a minimum.
Combine ingredients. Combine all chopped vegetables with other ingredients into a large pot, heat to boiling and let simmer for 10 minutes to blend the flavors. You can taste test it at this point, but keep in mind that flavors will continue to mature after the salsa is processed and that allowing the salsa to simmer too long (as you add more ingredients) will continue to break down the consistency of your vegetables. Plan accordingly.
Fill jars. Ladle hot salsa into warm jars. A canning funnel or a disposable cup with the bottom cut out helps keep the mess factor down. Fill jars to 1/4 inch from the top of the jar and wipe off the rims. Once filled, use tongs to put a hot lid on top of each jar, securing with the canning ring. (Keep lids hot by putting them in a small sauce pan and allowing to simmer while you fill the jars.) Screw on the lids finger tight, meaning that you use your fingers to tighten the rings then undo a quarter of an inch.
Process. Carefully put the jars of hot salsa (with lids and rings) into the water boiling in your water bath canner or stock pot (as many as can fit in the pan without them being wedged together). A wire basket makes this process much easier, but tongs can also be used. Be sure the tops of the jars are covered with 1 inch of water. Reduce heat enough to maintain a roiling boil and allow jars to process for 15 minutes, uncovered. Put a dishtowel on your counter top, and when jars are processed, use tongs to lift them out of the water and put them on the dishtowel to begin the cooling process. After about half an hour, when the jars are cool enough to touch, turn them upside-down to ensure proper sealing. Allow jars to cool for at least 24 hours before moving.