You can use green or red tomatoes — red tomatoes result in a lovely colour, but the jam is very sweet. All the usual rules for jam-making apply.
2 lb tomatoes
1 vanilla pod
2 lb sugar
1/2 pint water
In a wide preserving pan, boil the sugar and water to a syrup. Add the peeled and sliced tomatoes. Boil steadily, stirring fairly often, for 35 minutes. Put in the vanilla pod and boil more vigorously for 10-15 minutes, until setting point is reached. Remove the vanilla pod, skim off any scum, and leave to settle for a few minutes before pouring into small jars.