I warn you, this is taking a while. I put sliced tomatoes in the oven yesterday morning at 9:30, to dry them. I finally turned off the oven eight hours later, and I left the two trays of tomatoes in the oven overnight.
I had the oven on at 90ºC (195ºF), bottom heat only, fan on. Maybe I should have turned it up a little bit more. As I described yesterday, the little tomatoes were just sliced in half, core removed, and arranged on oven pans on parchment paper (papier de cuisson). I didn't season them. No oil.
There they are above, in the process of drying in the oven. You can see that they aren't cooking, but just getting dehydrated. I didn't turn on top heat because I didn't want those on the upper rack to scorch on top.
When I opened the cold oven this morning, Here's what I found.. And they weren't yet sufficiently dry. Still soft. Kind of sticky to the touch. Not "leathery" enough. I was able to consolidate the two pans and put all the tomatoes on only one. Back into the oven they went.
This time, I turned the oven on top and bottom heat, at the same temperature, with the convection fan going. Now the tomatoes are all on the bottom rack, so they shouldn't get scorched. I think the reason they weren't totally dehydrated this morning is that our weather is so warm and humid right now. Walt said the relative humidity yesterday morning was 99%. That's unheard of here. This morning the weather is warm and fairly muggy. I'll just have to keep an eye on the tomatoes and make a decision about them later. Dried enough? Not dried enough?