I’m into making jam. Last night it was tomatoes. The process was largely the same as all the other fruit jams I’ve made. Peel (easier than you think), seed (tedious but I’ve had worse experiences), chop (my knives are dull1).
They did cook significantly longer2 than the other jams I’ve made simply because of the water content. This made the yield poor. For a little over 5 lbs of roma tomatoes I made just shy of 2 pints of jam. It came our tasting really good. I have to say it tastes like someone made really good tomato soup and at the last minute tossed in a handful of strawberries. I wouldn’t have guessed that sweetened and concentrated tomatoes drifted toward strawberries.
In terms of making, this is the third batch of fruit that I’ve had to blanch in order to peel. I’m much more comfortable with the idea of dropping a seemingly delicate piece of fruit into boiling water and watching until the skin starts to loosen. The sugar to fruit ratio was different too and I’m trying to pay attention to what might indicate the difference. In this case I’m guessing that there was so much water that needed to cook off that the sugar/fruit ratio was based on the reduced weight of the tomatoes and not the saturated weight. I’ll do this recipe again next year but not before I venture into crushed tomatoes and the handful of other tomato preserves for which I have recipes. Also, while the recipe is really tasty, it’s not the kind of thing you smear on just anything. I’ll have to be pretty intentional about when and how to use it. To that point, it’s probably a good thing that it reduces so much.
If you don’t have a french oven, buy one. They are indispensable. The preserving pan of the guy that got me into jamming is a $250 copper preserving pan. My $75 french oven does that and everything else. I bought mine at Costco but this one looks pretty darn close and I like the other Lodge hardware I have.
I’m not a gadget guy. I actually pride myself on knowing enough about the tools and techniques that I’m doing to avoid needed specialty tools. That being said, I really enjoy making jam and there are a few canning specific things that I would recommend you have.
 I’m going to get my knives sharpened tonight but I’m on the hunt for the right sharpening system/technique. When I land on one, I’ll write it up.
 Most jams boil for ~8-10 min. The tomatoes were 30 minutes.