I have a handwritten page with the title of Green Tomato Preserves as per B L Keith, my maternal grandmother. This was written out by mother at some time in the 1950's, as well I have another sheet with the same recipe in my mother's writing from around 1967, when she wrote it out for my brother.
These are not a jam, and not a relish and not a fruit dish, but a preserve, lots of sugar, and used as an accompaniment to meat, or on toast as a spread.
Trim and stem tomatoes, place in kettle and pour over boiling water, let stand 5 minutes, drain off and begin to slice the tomatoes, thinly.
You need a large bowl or a preserving kettle to slice into, as this is a lot of stuff. Slice the tomatoes thinly, and layer with sliced lemon, sugar ginger and raisins. This will take several layers.
Cover the filled kettle with a cloth and let stand overnight on a counter, do not refrigerate as this is to draw the juices from the tomatoes.
Drain off the juice in the morning, boil and skim the juice for 10 minutes.
Add the fruits back into the juice and boil until the tomatoes are clear. You need to stir constantly in a figure 8 motion to keep the fruit from scotching and from boiling over. It does need to be a rolling boil, not a simmer, or it won't cook the tomatoes well enough.
When the tomatoes become clear put into sterile hot jars and seal with hot lids and rings.
I think you could use any citrus fruit, but the key is to thinly slice the tomatoes and lemons, using a mandolin if possible to keep the slices uniform. The thinner the slices the quicker they will clear when cooked.