Step 1: What You'll Need
1 kg tomatos
1 red onion
5 cloves of garlic
1 tea spoon salt
1 tea spoon honey
1 fistfull of fresh coriander/ cilantro.
You will also need
Vacuum packer or heat sealer
Step 2: Chop and Boil
Let it simmer until the volume is reduced aproximately by half. Leaving a couple of tomato stems in while it simmers ads a nice tomato aroma that the tomatos themselves can not give.
Pick out the stems again when the salsa has been reduced to the desired consistency
Step 3: The Bags
Fold the opening of the bags back before you fill them to prevent spilling salsa on them. For the heat sealing to work, the mating surfaces must be clean.
Step 4: Fill and Seal
Step 5: Boil Again
If you have a sous vide waterbath, you can of course do the sterilization there. If you have one with a rack to keep the bags apart, thats just perfect.
Since we are not boiling under pressure, it is important that the food has a pH value below 4.5 to stop the bacterium Clostridium botulinum from multiplying. C. botulinum produces spores that are resistant to boiling, but acidic conditions below pH 4.5 stops them from germinating. Tomatos can be highly variable in acidity, so to be sure, you should check the finnished product with pH strips. You can buy these in most aquarium stores. If you don't want to measure, you should find a recipe that uses vinegar or lemon juice to make sure the salsa is acidic enough.
The botulinum toxin produced by C. botulinum is one of the most potent neurotoxins we know, so this is not something to be taken lightly.
Step 6: Store and Eat
This method of canning can of course be used for anny kind of food that is handy in a bag.