You can make your own roasted red peppers instead of buying them. This makes great leftovers--just assemble the sandwiches right before eating.
You can also fry the eggplant rounds instead of grilling. Pour canola oil about 1/2 inch deep in a cast iron skillet or heavy pan. Heat over medium-high heat. Wipe salted eggplant slices dry with a paper towel. Working in batches, fry eggplant until golden brown on each side. Lay cooked eggplant on a plate lined with double sheets of paper towels, because eggplant soaks up a lot of oil.