Salsas are usually mixtures of high acid foods, such as tomatoes and/or fruit, with low acid foods, such as onions and peppers. With the addition of lemon juice, citric acid, or vinegar in the right proportion, salsa becomes a high acid food and can be safely processed in a boiling water canner. However, only research-based recipes should be used. Other salsa recipes, found on the internet, in published books, or from grandma’s recipe stash, should not be home canned unless they have been properly tested for safety. Enjoy those salsas fresh, or frozen for longer storage.