Preheat the oven to 175 or 200.  It doesn't really matter.  I used 175 convect.  Line a cookie sheet with parchment paper.  Slice all the tomatoes and arrange on the cookie sheet.  Spray somewhat liberally with cooking spray.  Sprinkle a scant amount of kosher salt over the tomatoes.  Dry in the oven for up to 12 or more hours, releasing steam from the oven by opening the oven door every couple of hours or so until the steaming has stopped.  Remove finished tomatoes to a plate until all the tomatoes are done.  Once cooled, store in a jar and pour extra virgin olive oil over the dried tomatoes and store them in the fridge for up to 2 weeks.