I make various apple and onion relish for Christmas and use recycled jam jars and lids which have been sterilised on a hot cycle in the dishwasher. I fill the jars with hot relish whilst they are still hot... put the lids on tight... seems to work fine. I've never boiled the contents in the jars.
I make my jams like Cogito, except I sterilise in the oven. It's the way that my mother taught me and the boiling for ages in a water bath seems just so excessive. I know in theory there can be issues with botulism, but I haven't been able to find any evidence that botulism is a significant risk so I suspect it's one of those theoretical things that various government agencies have gone a bit overboard about.
The issue with using ordinary jars in a water bath is that potentially they can shatter. Again I don't know how likely this would be.
Another method I've heard used is called inversion, where you flip the jar over for a second or two after filling it (and putting the lid on obviously!). It's another way to get a good seal (which is the thing that really matters for storage, although my mother used circles of greaseproof paper plus a cellophane covering held on by a rubber band, and I don't recall ever being ill despite the occasional bit of mould).
2 cups water, 1/4 cup bottled lemon juice, 4 pounds apples, peeled, cored and diced/sliced, 2 cups sugar and 1 tsp ground cinnamon.
Combine water and lemon in a big pot. Add apples. Bring to boil and stir in sugar and cinnamon. Simmer until thickened (about 10 mins). Can in hot sterilized 1/2 pint jars. Process in a hot bath for 15 mins.
I did mine in 1 pt jars and skipped the water bath. Makes just enough for pie/crumble for four.