Roasted tomatoes are delectable little gems. Once you have them, you can use them in sauces, salsa, or just as a topping for bread: Voila! Bruschetta! Freezing is the easiest way to preserve their flavor, but if you have limited freezer space, canning is a good option.
There is, however, a catch. I’ve looked and looked and have been unable to find authoritative canning recommendations for straight roasted tomatoes (no onions). The recipe in the Ball Blue Book is close, with only 1 1/2 c. chopped onions for 12 pounds of Roma tomatoes—but for reasons that aren’t clear to me, this recipe recommends a processing time of 1 hour and 25 minutes. I cannot, for the life of me, figure out why you would need to do this. As you saw in yesterday’s post, the USDA recommends a 40-minute processing time for regular tomatoes. Why would they require twice as long for tomatoes cooked a different way? Is it because their recipe leave the skins on? Does the prolonged heat of roasting do something to the natural acidity of tomatoes? Is it a typo? I’m flummoxed by this. A couple of people at the Clark Park Farmer’s Market this past weekend told me that they treat them like cooked tomatoes (sauce, etc.) and simply process them for 20 minutes in a boiling water bath. Discussion topics on the internets are also inconclusive, with recommendations of everything from not safe, period (this is simply not true), to 20 minutes, to 40 minutes, to 80 minutes.
I can’t tell you why, exactly, but 20 minutes made me nervous. I did, after all, throw in some garlic and herbs and a little bit of oil. I eventually decided to compromise with 10 minutes in the pressure cooker with 15 pounds of pressure. If you don’t have a pressure cooker, I’m not sure what to tell you. If you have all the time in the world and are of the better-safe-than-sorry camp: sure, try 85 minutes. If you’re slightly more adventurous, you might try the regular tomato guidelines: 40 minutes. And if you like to live on the edge or have problems with authority, try 20 minutes…but you do so at your own risk.
About 10 pounds tomatoes
4–6 cloves garlic
a few sprigs of rosemary and thyme
A bit of olive oil
1) Cut the tomatoes in half and arrange them face down in a roasting pan. I was able to fit about 5 pounds in a big roasting pan, 2 1/2 pounds in a regular cake pan. Throw in some herbs and garlic and brush a little oil over the tomatoes.
2) Roast at 450°F for about half an hour (more or less depending on the size of the tomatoes) or, better yet, run them under the broiler for 3–5 minutes. However you do it, you’re cooking them until they’re crinkly with a few black spots.
3) Let them cool. Meanwhile, prepare your jars and lids. If you’re using a water bath, bring your water to a boil and sterilize the jars.
4) You can remove the skins, or not, depending on what you want to do with them (Blue Book leaves them on, which perhaps contributes to the longer processing time?). I remove them. Pack the tomatoes in pint jars and run a spatula around the edges to remove air bubbles. Add more if necessary. You’ll find that they shrink quite a bit. My 10 pounds yielded only 3 pint jars. Add some acid if you’re using a water bath: say, 1 T lemon juice, or balsamic vinegar might be nice. Wipe the rims and adjust the lids.
5) Process as best you see fit, as discussed above. Remember, the well-tested but conservative Blue Book says 85 minutes.