Bring a large pot of water to a boil, core and score the tomatoes, then blanch them for 10-20 seconds before transferring to cold water to cool.

Remove skins and seeds from the cooled tomatoes, then dice them into small pieces.

In a large stockpot, combine the prepared tomatoes, onions, green peppers, garlic, jalapeños, sugar, cilantro, salt, and vinegar.

Bring the combined ingredients to a boil, then reduce heat and simmer for 15-30 minutes until the salsa thickens to your desired consistency.

While the salsa cooks, sterilize canning jars and lids in boiling water for 1-2 minutes.

Fill each hot jar with salsa, leaving appropriate space at the top.

Use a canning spatula to remove air bubbles, wipe the rims with a clean cloth, and seal jars with sterilized lids.

Process the jars in a water bath canner for 15 minutes, ensuring they are covered by water throughout.

After processing, let jars cool gradually, check seals, and store sealed jars in a cool, dark place.