Slice tomatoes into ¼ inch slices, removing cores. For cherry tomatoes, cut in half.
Sprinkle with salt, if desired.
Dry in the dehydrator at 120º overnight, turning and drying for another several hours in the morning, or dry on a lightly greased baking sheet in the oven on its lowest setting – it may take up to 24 hours. Rotate the baking sheet occasionally and flip the tomatoes at least once in that time.
Let them cool, then pack in glass jars.
If you want to store them in the pantry, dry them until they are brittle-crisp. If you prefer them chewier, I recommend storing them in the freezer.