1. Prepare the Vegetables: Start by dicing the eggplant and zucchini into bite-sized pieces. Finely chop the onion and mince the garlic.

2. Sauté the Onion and Garlic: Heat the olive oil in a large skillet over medium heat. Add the onion and garlic, and sauté until fragrant and translucent, about 2-3 minutes.

3. Cook the Eggplant: Add the diced eggplant and 1/2 teaspoon of salt to the skillet. Cook for 5-7 minutes, stirring occasionally, until the eggplant begins to soften.

4. Add the Zucchini and Tomatoes: Stir in the diced zucchini, the can of diced tomatoes (with their juices), tomato paste, oregano, basil, and red pepper flakes (if using). Season with the remaining salt and black pepper.

5. Simmer and Serve: Reduce the heat to low, cover the skillet, and simmer for 15-20 minutes, stirring occasionally, until the vegetables are tender and the flavors have melded together. Finally, remove the lid and sprinkle the Eggplant and Zucchini Sauté with fresh chopped parsley or basil, if desired. Serve the sauté warm as a side dish or a light main course.