1. Cut up the tomatoes, skin and slice the onions, and put all the ingredients into a saucepan. Simmer until soft.
2. Rub through a nylon or stainless sieve, re-heat and continue cooking until the texture is as thick as required.
3. Bottle, leaving a headspace, and seal at once. Label when cold.
4. Note Red tomatoes give a better colour to this brown sauce than green ones, but either can be used.
To sterilise bottles see
Sterilising Bottles.