You are very gracious to want to make something special for your friends and relatives this holiday season, but do you crochet? Or knit, perhaps? They might feel more comfortable with a nice pair of socks. Or a muffler.

Without beating around the bush any further, you must sterilize canned foods each and every time you seal them up. (And really, you don't want to seal them up too many times, because a tomato can only take so much cooking.)

The especially notorious spores that people are most concerned about - the ones that cause botulism - only thrive and become poisonous in an oxygen-free environment. That's why fruits and vegetables are sealed and then subjected to the intense heat of pressure canning - to ensure that the spores have been destroyed. Your Hunt's or Del Monte or generic store-brand canned tomatoes have been safely stored in the can, but once you open them and especially when you mix the tomatoes with your other ingredients, you expose them to all sorts of potential contaminants and must start the process again. If the salsa is to be sealed away in a jar for one of your relations, it must again be sterilized using a hot-water bath if the mix is highly acidic or with a pressure canner if it is not. (Most salsa recipes require pressure canning).