Heat the oil and fry the vegetables in it until the onions are translucent. Add the tomatoes and the ketchup and bring to the boil. Season to taste with salt, pepper and chilli peppers.
Pour full to the brim in clean glasses, close and simmer for 20 minutes at 90 ° C in a saucepan.
The glasses last at least 1 year. The tomato-zucchini tastes cold with a snack, but you can also eat them warm as a quick pasta sauce or to bake meatballs or something similar.