First cut the eggplants, tomatoes, potatoes, zucchini, and mozzarella balls into thin slices and set everything to the side.
Add the oil to a cast iron skillet and cook the onions and garlic. Add the red and yellow bell peppers and stir vigorously. Top everything off with the tomato sauce and season with salt and pepper while the mixture is simmering. Stir again and sprinkle the fresh basil over the sauce.
Take one slice of each of the sliced ingredients from Step #1 and place them upright and next to each other around the outer edge of the pan. Repeat this until you have filled the outer edge with a complete circle, and then continue with a smaller circle inside. Repeat until the entire pan is full.
Cover the pan with aluminum foil and bake the dish in the oven at 350°F for one hour.
Use a spoon to distribute pesto in a circle around the dish, making a pesto ring. This will make the delicious dish look (and taste!) even better.