There are 2 types of canners ( not cookers) water bath and pressure canners. IF you use a water bath canner for salsa you MUST have at least 1 cup of acid; i.e. vinegar, lemon or lime juice to have it safe to can by that method. The preferred way is pressure canning. The problem is the amount of low acid ingredients in the salsa. I have water-bathed my salsa but have a weight for my pressure canner now so I can go back to using that. All canned produce must be processed to be safe according to the home canning experts and Ball Blue Book. Older methods once used are no longer considered safe. Maybe they are over cautious BUT I will go with their recommendations rather than risk botulism. Just putting hot contents in a sterilized jar is NOT enough any more. The filled jars must be processed either in a water bath or pressure canner. All low acid foods should be processed in pressure canners.