Boil the ketchup at an average boil, stirring and removing the foam, so that the sauce is boiled at least 1/4 part, and you can longer if you want the density. A couple of times you can once again punch with a blender.
For 15 minutes until ready to sterilize the cans, I do it in the oven all at once, to do this, put the wet cans on the grill with the neck up, hold at 200 degrees for 15 minutes (400 ml cans)
Sterilize the lids in water.
5 minutes before the sauce is ready, pour in the vinegar.
Then take 1 jar out of the oven (carefully, very hot), pour boiling ketchup into it to the top, immediately seal it.
Let cool upside down on a towel. From this amount of ingredients, I get 17-19 cans of 400 ml.
Store in a dark, dry place, just at home.