Served on a platter that shows off its contrasting colors, this dish looks like a colorful Cubist still life.
Heat in a large skillet or Dutch oven over medium heat:
Add and cook, stirring, until golden and just tender, 10 to 12 minutes:
Transfer the vegetables to a plate. Add to the pan and cook, stirring, until the onion is slightly softened:
Add and cook, stirring occasionally, until the vegetables are just tender but not browned, 8 to 12 minutes:
Add:
Reduce the heat to low, cover, and cook for 5 minutes. Add the eggplant and zucchini and cook until everything is tender, about 20 minutes more. Taste and adjust the seasonings. Stir in: