Driving home this weekend, from Boston to Orlando, left me with lots of time to listen to the radio. Molly Katzen was being interviewed on one of the channels and gave a convincing speech about when to salt roasted vegetables.
Her POV was that salting before sucked too much moisture out of the vegetables and caused them to steam in the oven, rather than roast. It sounded well and good, but I didn't agree. My experience with salt never produced so much moisture that it would steam anything in the oven. A frying pan? Sure. But not in the oven.
I tried both ways this weekend and am still sticking with my initial opinion. The vegetables I salted before roasting did indeed give off a bit of moisture -- a few beads of dew, if that -- which created a nice caramelized crust on the vegetables.
The unsalted veggies charred more in the oven and became very dry, almost dehydrated, even with a coating of oil.
I used a roasting pan for both experiements, with a single layer of vegetables. I also did a batch using a sheet pan. The only way I can see Molly's theory coming true is if the pan was overcrowded with vegetables, keeping them from being surrounded by hot air at all times.
Have you tried the salt/no salt roasting? What is your preference?