Clean, wash and chop the tomatoes. Pass them through a meat grinder or juicer.
If you prefer your tomato juice to be seedless, then you need a juicer with a deseeder; I don't mind so I didn't use a deseeder.
Discard the foam that results from the juicing and add black pepper and salt to taste. Optionally, add finely chopped parsley.
Pour the resulting juice into clean bottles, close with caps and sterilize for 15 min. after boiling point.