Tomatoes aren't high acid, so they need the addition of vinegar or lemon juice in order to safely can with a hot water bath. Honestly, I'm not sure why you would want to make tomato sauce from canned tomatoes because for me, the whole point of canning tomatoes is because the tomatoes will otherwise go bad. But anyhow...
I recommend finding a tomato sauce recipe from a canning cookbook or recipe website. Here is a recipe I found from the Ball website which is a reputable source, and here is an article about hot water bath canning tomato sauce. Notice that the recipe calls for a high acid ingredient, which is extremely important in canning tomato sauce with a hot water bath!
Secondly, it is NOT okay to seal jars by inverting them!!!! Get yourself a book about canning, Ball sells several good ones (Blue Book and Complete Guide to Home Preserving) and learn about the canning process. The steps are as follows:
(0) Follow the recipe EXACTLY, don't add any other ingredients that may change the pH of the final product!
(1) Get the hot water boiling in a jar large enough to have a few inches both above and below the jar that you'll use. You can use a metal trivet or canning rings to act as a base for the jars so that they have water going under them and aren't touching the base of the pot directly.
(2) Start with jars that are appropriate to canning and have fresh lids (or clean, working reusable lids like Weck jars or Tattler lids). If processing for under 15 minutes the jars need to be sterile (can be made sterile in a hot water bath). Inspect Tattler seals for any nicks, and throw away the bad ones.
(3) Normal canning lids and Tattler lids need to be prepared by soaking in hot water right up until use.
(4) Add the ingredients to your jars, remove air bubbles with a spatula, wipe the rims clean, and apply the lid as per the instructions of your lid. (Regular Ball lids are slightly different from Tattler lids, and I've never used Weck jars which I think are different again.)
(5) Insert into the hot water bath with canning tongs, cover, make sure that you start the countdown once the water has returned to a full boil.
(6) Remove once the time is up. Don't tilt the jars when removing them as the seal isn't airtight yet. Check the instructions for your lids, at this point Tattler lids have to be tightened fully.
(7) Leave the jars alone to cool. After a few hours or overnight, check the seals by trying to gently pry open the can. They should be "finger tight" and not pop off. The jars that aren't properly sealed can be put into the fridge and consumed within a short time. Otherwise they're good for up to a year or whatever the recipe suggests.
Increasing the size of the jar generally increases the canning time. When processing, you are heating the food all the way through to a particular temperature to kill any microbial contaminants. For an item with more volume, it will generally take longer to bring the center up to a particular temperature.
How long you have to process it depends on how big of step you take in the size of the jar, and what you are canning. I would imagine it would usually add 5-10 minutes to the processing time.
Here is a link explaining it. It also refences the USDA canning guidelines. The second link includes canning times for many items; most increase with larger volumes, but not all. These should get you started, and you can research further if you are canning something that isn't in these documents. I suppose there is a general processing time that is safe for any size, but it would probably affect the flavor and texture of the food to process it too much more than is necessary.
NOTE: While I may play fast and loose with some USDA guidelines, canning is ALWAYS serious business. Improperly canned foods can lead to botulism, which is hard or impossible to detect, and you can't "cook it" out of the food. Use tested formulas and correct procedures.
PS: Here is the direct link to the pickle guidelines. It looks like for anything larger than gherkins or sliced (bread and butter) pickles, you will add five minutes to the time. MAke sure though...
Best Answer
There are no current safe recommendations for home canning oils/fats as it’s considered unsafe for a verity of reasons. Although you are using alternatives for dairy many will still have high fat and oil content that can cause botulism which is a type of food poisoning that can lead to death. I would recommend that if you make a large amount of this sauce to freeze it instead and to not exceed storing it longer than a couple months. I know this can be really disappointing considering that it’s a vegan sauce and you probably would like the ease of “reach and pour” but I wouldn’t risk it. Please use your own discretion. https://www.healthycanning.com/fat-and-oil-in-home-canning/