
Cook the vegetables. Heat the olive oil in a large pan over medium-high heat. Add the onion and cook, stirring often, until softened, about 5 minutes. Keep stirring often as you add each vegetable. Add the bell peppers and cook for 4 minutes. Add the garlic and cook until fragrant, about 30 seconds. Add the eggplant and cook for 3 minutes. Add the zucchini and cook until the vegetables begin to brown, about 3 minutes.
Add the tomatoes and seasoning. Add the canned diced tomatoes, salt, black pepper, paprika, and cumin. Reduce the heat to medium and cook the tomatoes down, stirring occasionally, until reduced and the vegetables are tender, about 10 minutes.
Finish and serve. Remove the pan from the heat and stir in the sherry vinegar and parsley. Serve the pisto in bowls with crusty bread as an appetizer or side dish with meat or fish. If you’d like to serve it as a main course, top it with a fried egg.