Hi bhamcurry. I hope you enjoy your time in this Forum and that you will share some of your experiences here as I think there may well be an interest in what is possible with the canning process. I did consider canning base gravy as an alternative to freezing but finding out of the risks of botulism with low acid canning, have not actually tried it, despite acquiring the canner in the link some time ago. It seems a bit risky to me and freezing is a safer bet. I've had a brief look at the list of vegetables and the recommended pressure and cook times on the U.S site info and it's quite involved. So I'm not sure how a typical base gravy that you would find here, would fare. It would be interesting to hear how you do it sometime.
Thanks.
Bob
Bob, I have pressure canned a load of low acid foods such as meat stock, meat sauce. beans, and such like.
The curry gravy looks very much like a vegetable soup. Using the usual rule of thumb of "look at the ingredients list, find the one with the longest processing time, and process for that much time" results in a 55 minute @ 10psi (weight) or 11 psi (on certified gauge) time. I usually add another 5 minutes to be safe, hence the 60 minute processing time for the pint jars (500ml) of gravy that I put up.
If you include any meat your minimum processing time for a pint jar is 75 minutes. As always, look to the official sources - they adopt a belt, braces, spare belt, and extra braces approach to food safety because the consequences of getting it wrong are so horrifying.
I also use a weighted gauge that I bought from amazon.com for my pressure canner. Getting the pressure gauge to the county extension service for certification, while free, is a pain in the bahookie and the weighted gauge is a no-maintenance addon well worth the cost

For reference I bought this one:
https://smile.amazon.com/Presto-50332-Pressure-Canner-Regulator/dp/B000HMBVQ8/This weighted gauge allows you to compensate for your height above sea level. The higher you are, the more weight you need to add, and the longer the processing time. Where I live is less than 1000ft above sea level so I don't need to adjust my processing times - these adjustments are all laid out clearly in the USDA guidelines.
I hope all of this is useful and not too much info?