Late this summer (and continuing into the fall) we've been drowning in tomatoes. We planted a bush in our little raised beds in the spring and it's been completely out of control, then we got even more from a summer CSA. I've used some in dinners and elsewhere, like salsa, but there's still too much. So I learned something new: how to can. These are like a can of whole peeled tomatoes you'd buy in the store, they're just in mason jars instead. It turned out we had all the supplies needed, though my setup isn't what you might see in a canning kit. The important thing is you have mason jars, a big pot and a way to keep the jars off the bottom where it gets hottest, like a strainer. Yes, it turns out you don't need a pressure cooker to can. It was news to me.
The first time I tried this I had several pots of water boiling and the process was very inefficient. The second time I'd learned a few things and it went a lot faster and easier. I'm glad I waited until the second attempt to write about it and, more importantly, take pictures. I learned how to do this from The Spruce Eats, here's their page on it. What I've been doing is similar but also a bit different.
What you need:
~10 pounds tomatoes (we've primarily had Heirloom)
Lemon juice
4 quart sized mason jars (wide mouth preferred), w/ lids and rings
A gigantic pot w/ strainer (ours is a 24 quart Bayou Classic)
Some large bowls, knives and a cutting board, water
A tea kettle (maybe)
Quick version:
1. Mostly fill the pot with water (strainer inserted), put on stove with burner set to high
2. Wait for water to boil, this'll take a while
3. While waiting, slice an x in the bottom of each tomato and prepare an ice water bowl
4. Once water boiling, blanch the tomatoes (boil ~1m then put in ice bath) - do in batches
5. Bring water back to full boil then put in the mason jars/lids, leave for 10m to sterilize
6. Core and peel the tomatoes, I toss the skins
7. Add 2 tbsp of lemon juice to bottom of each jar
8. Cram tomatoes into jars, I quartered the large ones and used muddling tool to push down
9. Fill jars to half inch from top with boiling water (if necessary), then put on lid and ring
10. With water boiling, carefully submerge jars (into strainer inside pot), leave for 45m
11. Pull jars out and leave on countertop for 24 hours
12. Check seal, date and put in storage until ready to use
Getting the right amount of water to start is a bit of a guessing game, because when you add the 4 full quart jars later you don't want it to overflow, but you also want to them submerged in the water. Eyeball it to start and adjust later.
With so much water it'll probably take 30 minutes or more to boil. I started it before taking a shower and getting dressed for the day and still had time to get everything else ready. It's worth the wait because you can then do everything in this one pot of water: blanch the tomatoes, sterilize the jars and seal them with the tomatoes inside.
Blanching the tomatoes isn't all that hard. You definitely will need to do this in batches to get them all done and it's kind of active work since each tomato should only in the boiling water about a minute. Then you need to immediately put the hot tomatoes in an ice bath to bring the temperature back down. Where this step gets tough is logistics. There's a lot of tomatoes to be moving around and after each batch the ice has melted. You're just moving a lot of stuff around, so make sure you have enough bowls and are ready to do that.
Once the blanching step is done, and probably before you start peeling, bring the water back to a boil to sterilize the mason jars. I used a slotted spoon to pull out some tomato skins that'd been left behind in the pot. You want to sterilize to ensure food safety. 10 minutes for the jars and lids ought to do it. Use tongs to remove and place on cooling racks while you get back to the tomatoes.
Peeling after blanching is surprisingly easy, but it is very messy. The skins are basically removing themselves coming out of the ice bath if you cut a decent sized x on the tomato bottoms before boiling. Use a sharp knife to cut the top and bottom core (non-flesh) parts of each tomato, plus any bad spots. Then pull off any remaining skins with your fingers. Place in bowls until you're ready for the next step. There'll be a lot of juice so you may want paper towels to keep the mess under wraps.
At this point you should have sterile mason jars and lids and all the tomatoes blanched and peeled. Next, before adding the tomatoes, add 2 tbsp lemon juice to each jar. The purpose of this is supposedly to raise the acidity level so, on sealing, the tomatoes will still be safe to eat. Each tomato variety has slightly different acidity but, instead of determining whether or not I need to do this, it's easier just to always do it every time.
Now it's finally time to add the tomatoes to the jars. At first it'll look like there's no way that many tomatoes will fit into the jars, but you can really push them in there. To do this most efficiently I quartered a lot of the larger tomatoes for space purposes and then used a muddling tool (that I have for bartending) to really push them down. It's fine to crush most of the tomatoes, they don't need to stay whole. Fill until there's only about a half inch left to the top. If there's any more you'll want to fill with boiling water from a tea kettle. Last time I did this I didn't need to do this and there was only a half tomato left over, perfect!
After covering (with a round lid) and closing the mason jars (with the ring over the lid), place them into the big pot when the water is boiling again. This is somewhat tough since the jars are now heavier and you don't want to splash the hot water everywhere. To be honest I should've just used the strainer to do this. The jars need to be off the very bottom of the pot anyway and the strainer would be the easiest way to put them in. Even as I'm writing this up I'm learning a lesson for next time. All of the jars need to be submerged in water about one inch. You may need to add, or remove some, to get the level right, and that's okay.
Leave the jars in the boiling water for 45 minutes, then remove them. The strainer is probably again the best way to do this, because trying to get them out with tongs and a big plastic spoon was a real challenge. Place the now sealed jars on the countertop and let them sit for 24 hours or so. You're basically done!
The next day you can check the seal on the lid. If it's stuck on there, without the ring, you're good to go. I wipe down the jars, which are at this point covered in a salt-like residue (I'm assuming from the tap water), write the date on the lid with a sharpie and put them in our pantry. The tomatoes are now preserved, basically forever (though best used within a year), and can be used whenever we might need or want them.
Anyway, that's it. This was always something I was more or less scared to attempt but it's really not that bad. The more you know.
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