Seasonal Tomato Sauce in a Jar 🍅

Author: Olivier Karfis

Every year, around the beginning of September, I take on this labor of love project of creating tomato sauce for the winter months.

We absolutely love tomatoes but because we try to be conscious of vegetable seasonality, we do not buy tomatoes in the middle of winter… they don’t taste good anyway.

Let me walk you through the steps of making your own tomato sauce jars… It’s simple yet very time-consuming. While doing it, you’ll wonder why you put yourself through it. But in the middle of winter, when it’s dark out at 5 PM and you pull out a jar of fresh tomato sauce, you’ll only feel the joy and remember none of the pain, trust me :-)

The ingredients for my tomato sauce

The best tomatoes (you can get your hand on) – les meilleures tomates (f)
I would go with organic (“Bio”) or at least tomatoes that were grown in the ‘organic’ spirit (with no chemical-based pesticides). In my case, I’m lucky that the dad of one of Leyla’s friends owns a small organic farm and I just let him know that I’ll buy his tomatoes when they are ready and plentiful. This year, I got 20kg! (44lb). Tomatoes can be overripe (actually preferred) as long as they are not rotten.

A bunch of basil – un bouquet de basilic
The amount completely depends on how flavourful you want to make your base tomato sauce. I tend to go with a very neutral base (less basil) so as to be able to use it in every kind of dish possible. If you tend to only use your tomato sauce in Italian style recipes then add more basil. I add just enough to give it a subtle flavor but not enough to earn a ‘basil tomato sauce’ label.

A small number of onions – quelques oignons
Around a medium size onion per 2kg (4lb) of tomatoes

Garlic – de l’ail (m)
Around a clove per 2kg

Salt – du sel

Pepper – du poivre

Olive Oil – de l’huile d’olive

Ingredients for tomato sauce jars

The tools for my tomato sauce

A HUGE saucepan
Obviously, if you are preparing 20kg of tomatoes, you are going to need a very large pot. I’m lucky that my step-dad used to be a professional chef and still has some of his massive pans that he can lend me. You will need to find a source to rent/borrow/steal a really large pan. You could try to do it in batches but then the process is even longer. Good luck!

Some large bowl/containers
You’ll need to store the tomatoes as you prep… Again, did I mention 20kg?

Canning jars
The goal is to keep this tomato sauce for 3 to 12 months (or more) so you’ll need some glass jars with lids. There are several styles available (with screw lid, with metal clasps…) use what is available in your area and what you prefer. I like the re-useable screw top style from the brand Le Parfait. I’ve never had any troubles with them and you just need to replace the little top every time you use them (see below).

Lots of clean rags/towels/kitchen towels*
You’ll see why later…

The prep of my tomato sauce

Clear out your Saturday and start early!

The first thing you will need to do is prepare your work area. You’re going to have to build a little chain factory to optimize your time. If you have one (or more) persons helping you then even better, each one can have its own task.

The longest part to this process is to peel the tomatoes and remove the seeds.

  1. Set up a large pot of boiling water.
  2. Take 5-6 tomatoes and with a sharp knife, make an X mark into the skin of the tomato (try to just make it skin-deep and not cut into the flesh too much).
  3. Once you have these 5-6 tomatoes ready, drop them gently in the boiling water for 10 to 20 seconds max.
  4. Remove them from the boiling water with a strainer and quickly plunge them in cold/icy water to cool them as quick as possible.
  5. Once cooled, remove the tomato from the water then peel the skin off by pulling on it with a knife.
  6. Cut the tomato in half along its horizontal middle (equator?) to expose as much of the seed pockets as you can.
  7. Set aside and repeat the peel and cut for the other 5 tomatoes.

Now, put your knife down and with your fingers, remove as much of the pulp and seeds as you can. Don’t be afraid to get in there, it’s the fun part!

Set aside the ’empty’ tomato halves in another container and repeat all the steps above until you can’t stand tomatoes anymore!

Removing seeds - tomato sauce jars

If you are working by yourself, it’s important to get a rhythm in place. If you did all these steps individually in sequence, it would take twice as long. So batch your operations and make sure, after you are comfortable with the sequence, that you always have a batch of tomatoes in the boiling water and or cooling while you prep another batch. The goal is to never have to wait from task to task.

Prepping 20kg of tomatoes by myself took a continuous 3 hours and 15 minutes. A labor of love!

Peel the onions and dice them into small cubes, peel the garlic and chop into small pieces, wash and remove the stalks from the basil leaves and chop roughly.

The cooking of my tomato sauce

In the extra large pot, eat up some olive oil on medium and add your onions. Let them soften up without taking on much color. Add your garlic and roast for another 2 minutes while constantly stirring.

Take the tomato halves in your hand and squeeze them over the pot to squish them as much as possible. Repeat.

Crushing the tomatoes

Add pepper and salt (be careful to not over-salt since you will most likely correct the seasoning when you actually cook the sauce a few month from now). Cook the sauce for about 15 minutes after the last tomato is in. Add the basil and cook for another 10 minutes.

The canning process of my tomato sauce

So the concept here is as follows: put a really hot mixture into a sterile glad jar with just a little bit of air space. Cap it with an (expendable) hermetic seal on it and then boil the whole jar for at least 45min to get all the air inside the jar to expand and exit creating a seal.

The Le Parfait jar system uses a metal lid that has a small rubber seal, that lid is held in place with a screw top lid while the jar is in the boiling water. After the canning (jarring?) process, the lid is now completely sealed and you can even remove the screw lid which is not necessary anymore (I keep it on so I don’t have a whole box of screw lids). Once you want to consume what is in the jar, you pierce it with a small tool, this breaks the seal and you can then throw it away. That’s the only piece that needs a replacement for the next round.

Le Parfait also has lids with a big orange rubber seal and a built-in glass lid with a clasp. You go through the same process and then break the rubber seal once you are ready to eat. Then buy replacement rubber seals…

Sterilizing the jars for my tomato sauce

First, wash all the glass jars thoroughly (a dishwasher is great for that). Then in a large boiling water pot, dip the utensils you are going to use (a ladle and tongs) and fully submerge the glass jar (I do them 2 by 2). Leave in the rolling boil for 30 seconds and then, using the tongs, carefully empty out the water and set the jar onto a clean dish towel.

While the glass is still hot, pour in the hot tomato sauce all the way up to the mark. Make sure that you do not put any sauce onto the rim of the glass which would impact the seal. If you do, clean it up thoroughly with a clean paper towel.

Note that depending on the sort of tomatoes you used, the sauce might be too watery. If that is the case (which it was in this batch), then instead of a regular ladle, use a mesh ladle to remove liquid as you fill in the jars.

Once the jar is filled up, set the sealing lid on top and then screw in the metal lid. Per the Le Parfait instructions, don’t screw them very tight, just enough so that the sealing lid is maintained in place.

Repeat the process, 2 by 2, for all jars. With the 20kg of tomatoes, I ended up with 13 jars (11x750ml and 2x250ml) so around 8,750kg of sauce.

The sterilizing process for my tomato sauce

Once all the jars are filled and screwed-in. Put them all in a very large pot separated by clean dish towels. Why? so that they don’t bang against each other while they are in the boiling water. Then set the whole pot on the fire and boil for 45 minutes after the water starts to boil. Then turn off the heat and leave until the whole thing cools down (I left it to cool down overnight).

Remove the jars from the water. Dry off and unscrew the lid to check that there is a good solid seal between the glass jar and the rubberized lid.

You are finally done!

When you are ready to eat your sauce, using a knife or sharp utensil, pierce the top of the lid to break the seal and discard. Make sure you first smell then taste the ‘raw’ sauce before you add it to whatever dish you are making… just in case something went wrong.

I’ve been doing these tomato sauce jars for 4 years in a row now and never had any jar ‘fail’. This year, I used the last small jar I had more than 14 months after I had made it and it was as good and fresh tasting as the day I made it.

It’s a lot of work and cleanup, it’ll take you the bigger part of a day but in the end, the result will be worth it!

À vos fournaux ! (lit: at your burners – French expression meaning let’s cook!)

Author: Olivier Karfis

Olivier Karfis

I'm Camille's husband. I handle all the marketing, technical & design aspects of the site and our apps. I sometimes cameo on some of the French Audiobooks recordings.

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