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Making Tomato Conserva

September 19th, 2017

Many years ago, I purchased the book ‘Cooking by Hand’ by Paul Bertolli. This book is part cookbook, part biography, part cooking theory; recipes are interspersed with stories of how they came about and recommendations and theories for making food even more delicious. While reading through the section on tomatoes, I came across the recipe for Conserva and immediately knew I wanted to make it. It’s not a difficult recipe, but it does take some time. The final product makes it worth every single minute, you won’t find a better way to preserve tomatoes.

This rich, concentrated tomato paste (though calling it paste is a bit derogatory as it’s nothing like canned tomato paste), is like a ripe summer tomato intensified in a jar. Because it’s not cooked at a really high temperature, it has a completely different flavor than many cooked tomato sauces. The sugars seems to intensify and the fresh tomato flavor comes through quite clearly. Overall I’d say it’s much brighter than other cooked and canned tomato products, which almost end up with a heavy bitterness from the heat of cooking. Conserva is a bit of summer tomato heaven in the middle of our long Maine winters. It is such a versatile pantry staples; a small spoonful can be stirred into sauces to add a richness and depth of flavor, add it to canned tomato sauces to make it thicker, a spoonful in broth will add another layer of flavor to soup. We really enjoy it spread on sandwiches made of olive bread, eggs, arugula, bacon, and cheese (a bit of a BLT with conserva taking the place of fresh tomato).

In the book his recipe starts with 5 pounds of tomatoes, I find this size of a batch to be way to small. The final product is only about a cup of concentrate. I always double it, both because I want lots of it in my pantry, and because I like to maximize my time. If I have the oven on for 7 hours, I may as well have it full. Typically, my batches start with 10 pounds of tomatoes (though I make two 5 lb batches separately and put them in the oven together), from this amount I end up with a pint of conserva. Generally, I make 3-4 batches each summer. I also add a branch of a tomato plant in the pan, it adds a wonderfully deep tomato flavor to the final product. Contrary to popular belief, the stems and leaves of tomato plants are not poisonous.

Here’s the basics recipe:
Dice 5 pounds mixed tomatoes, some paste, some canning, into small pieces. Add a splash of good olive oil to a large pan, pour in tomatoes, add a small tomato branch with leaves, sprinkle with a teaspoon or so of sea salt. Bring them to a rapid boil and cook for 2 minutes. Put through smallest plate on a food mill, there should be no seeds in the final puree. (If you’ve been looking for a nice stainless steel food mill, I highly recommend this one from Matfer. I bought mine 7-8 years ago and LOVE it. Previously, I was using an old aluminum Squeez-O and wasn’t super keen on my food coming into contact with the aluminum. I use this one all the time, for making applesauce, pumpkin puree, tomato puree, and pureeing soups.)

Lightly oil a large casserole dish, I prefer to use glass since tomatoes are very acidic. (My favorite are these borosilicate glass pans from Marinex, I have several of them and use them constantly.) Pour puree into pan, place into a 300 degree oven, convection is best, but not necessary, but it will take longer in a regular oven. Cook for 3 hours, if not using convection add another hour or two to the time. Stir occasionally with a spatula, when you notice the surface start to darken, reduce heat to 250 and continue cooking for another 2 1/2 to 3 hours, or until it is thick, shiny, and brick-colored. Your final amount will be about 1/10 of what you started with, 1 cup of paste is about what you will end up with this batch (which is why I always double it).

Put conserva into a glass jar carefully pressing out any air pockets, cover with 1/2 inch of good olive oil. Paul recommends keeping the conserva in the pantry if you have a cool, dark space. As long as you maintain the 1/2 inch layer of olive oil on top it should keep. I keep mine in the fridge because my pantry isn’t always cool. Mine always lasts a year in the fridge if I am careful to maintain a layer of olive oil on top.

It seems a little complicated, but it’s not at all. In fact, most of the time is spent waiting and occasionally checking on the conserva in the oven. I make 3-4 double batches each year, it’s a staple in our pantry.

What’s your favorite way to preserve tomatoes for winter?

10 Comments to “Making Tomato Conserva”
  1. Nebraska Dave on September 19, 2017 at 8:50 am

    Susy, my method of preserving tomatoes this year has been just to put them in the freezer whole. I haven’t decided what to do with them later in the Winter when the stove heats up the kitchen. I really don’t like to have the oven on during the hottest part of the year and I still haven’t built my outside canning station yet. It’s been a busy summer with barely enough time for working in the garden.

    Tomato conserva sounds delicious but takes a little too much time and cooking for me.

    Have a great day in the kitchen.

    Reply to Nebraska Dave's comment

  2. kristin @ going country on September 19, 2017 at 10:20 am

    My favorite way is a roasted tomato sauce–sheet pan of sliced tomatoes with olive oil, salt and pepper roasted for an hour along with a whole head of garlic, then pureed in the food processor with fresh basil and red wine. No skinning required. Hooray. I freeze that sauce. We use it for pasta and pizza.

    But I am very interested in trying this, too. Assuming I can find a day to do it after this Indian summer heat wave is over and before I have a new baby in the house.

    Reply to kristin @ going country's comment

  3. val on September 19, 2017 at 12:12 pm

    I’ve been wanting to try this–thanks for the nudge!
    I don’t have the freezer space to freeze enough tomato sauce, and I dislike the flavor result of the amount of acid one has to add to make canning tomatoes safe, so this seems like a perfect solution. I am also thinking of getting a dehydrator to preserve cherry tomatoes.

    Reply to val's comment

  4. Rachel Bowman on September 20, 2017 at 9:51 am

    The thought of this conserve paired with a bacon sandwich sounds amazing. It’s still too warm here in the Midwest to have the oven on for so many hours, but I’ll bookmark this post for when the weather does cool down.

    Reply to Rachel Bowman's comment

  5. tonia on September 30, 2017 at 1:10 pm

    I am currently making a double batch the strained tomatos after cooking arw covered with liquid. Can some of this be strained off after going through the food mill to reduce cooking time and used as tomato juice or is it all required in the concentrate. Thank you for this unique and easy receipe

    Reply to tonia's comment

    • Susy on October 23, 2017 at 7:53 pm

      I would leave it in as it will concentrate as well.

      Reply to Susy's comment

  6. JessB on October 4, 2017 at 5:11 pm

    This is in the oven as I type. Convection would def be nice with it but it’s still chugging along without. Thanks for posting.

    Reply to JessB's comment

  7. Will on December 13, 2017 at 7:42 am

    I’ve been making a version of this with my trusty food mill but never really knew it had a name! Definitely going to give this a try. That is, if I can find some good tomatoes this time of year which are rare in my neck of the woods. May have to wait until summer.
    Thanks for sharing!

    Reply to Will's comment

  8. Lisa Knapp on August 20, 2020 at 11:19 pm

    2nd year making Tomatoe Conserva.
    Amazing flavor and color.
    Love the tomatoe branch/leaves.
    Had to hide the last 2 jars from my family last year after doing a little too good of a sales job.
    Thanks for the recipe!

    Reply to Lisa Knapp's comment

    • Susy on August 21, 2020 at 8:55 am

      It is a great one, we used all of ours up in March and have been longing for more.

      Reply to Susy's comment


This is a daily journal of my efforts to cultivate a more simple life, through local eating, gardening and so many other things. We used to live in a small suburban neighborhood Ohio but moved to 153 acres in Liberty, Maine in 2012.

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