Several pounds tomatoes of any size, washed and dried
Heat the oven to 250 degrees F.
Halve cherry and similar sized tomatoes; quarter larger tomatoes.
Line rimmed sheet pans with aluminum foil; grease with a bit of olive oil.
Place tomatoes skin side down on prepared pans. If you’re using different sized tomatoes, group like sized tomatoes together, using separate pans if needed. (Cooking times will vary according to size, and this will make the process easier.)
Sprinkle with kosher salt and place sheets in the heated oven.
Check on the progress once an hour and, as they get closer to doneness, every 30 minutes. Smaller tomatoes, like cherry or grape, will be done first. They’re done when reduced in volume by about half, the skin looks a bit leathery, and the inside still has some juice.
Depending on your oven, this whole process can take from three to six hours, but it’s worth it.