This article is from the Food Preserving FAQ, by Eric Decker email@example.com with numerous contributions by others.
>From Linda Merinoff :
HOMEMADE TOMATO PASTE
Push your tomatoes through a food mill. It's time consuming, but it gets
rid of the seeds which I think are bitter. You can also puree the tomatoes
in a processor or blender and push them through a sieve or chinnois to get
rid of the seeds. Or you can leave the seeds if you don't mind them.
[If you don't have a food mill, cut your tomatoes in half, get rid of
the tomato seeds with a finger, then rub the tomato halves through a
Spread the very liquid tomato on the flexible solid ring that fits into
the dehydrator. Sprinkle with a small amount of salt and put a few sprigs
of fresh basil in.
Run the dehydrator, stopping every hour at first to stir the mixture with
a rubber spatula a couple of times, making sure you stir every bit of it.
When the puree starts getting thick, stir every half hour. When it gets
almost to the right thickness (which is however thick you like it), stir
every fifteen minutes. All this stirring keeps the puree from burning or
When it's slightly less thick than you like it (it thickens as it cools),
stir again, remove the basil, and pack the paste into a jar just large
enough to hold it. Put a very thin layer of olive oil on top. Every time
you take some, put an extremely thin layer of oil on top again. Any extra
paste can be frozen.
For those of you as absent minded as I am, I once scooped half a jar out
to discard it, thinking it had gotten moldy. It hadn't. The oil on top
had solidified, as it often does in the fridge, and just looked weird.