I sliced up yellow squash, potatoes, zucchini, and eggplant. I used the grill pan for all of the veggies, but you could use a regular grill. If I ever do it again, I will sauté the thin potato slices in a separate pan. It took a long time to get them cooked through on the grill pan, much longer than it ever has in a regular sauté pan (I do potato slices like this for frittatas or egg pies). I wanted all of the veggies pretty much done, and then just leave the cheese to be melted. I started in the middle of the crust, and alternated veggie slices in an outward spiral until the obsessive child inside of me was warm and swaddled. I mean, until I reached the edge of the crust.
I didn't use any sauce, because I thought the finished product would be kinda juicy by itself. I was right. It was very good with just some garlic and olive oil on the crust (I used Trader Joe's pre-made whole wheat Tabula Rasa crust) and the oil and seasoning I used to grill the veggies.
