How to Make It
Light a grill. In a large, shallow dish, mix 2 tablespoons of the oil with the lemon juice, minced garlic, parsley and a pinch each of salt and pepper. Add the pork and turn to coat well. Cover and refrigerate for 1 hour.
Grill the eggplant, onion and garlic head, cut side up, over moderately high heat, turning a few times, until the vegetables are charred all over but not quite tender, about 15 minutes. Transfer the eggplant, onion and garlic head to a large, rimmed baking sheet. Grill the tomatoes, red and green bell peppers and zucchini over moderately high heat, turning frequently, until charred all over, about 5 minutes for the tomatoes and zucchini and 12 minutes for the peppers. Transfer the vegetables to the baking sheet.
Working over the baking sheet, peel off and discard the charred vegetable skins. Remove the seeds from the tomato and eggplant. Seed and core the peppers. Cut the tomatoes into wedges. Thinly slice the onion. Cut the eggplant, bell peppers and zucchini into 1/3-inch cubes. Remove the garlic cloves from their skins and trim off any charred parts. Pour any juices on the baking sheet through a strainer and reserve.
In a large, deep skillet, heat 1/4 cup of the oil. Add the eggplant and onion and cook over moderate heat for 3 minutes. Add the bell peppers, garlic, zucchini, oregano, cumin seeds and crushed red pepper and cook, stirring, for 3 minutes. Add the tomatoes and any reserved vegetable juices and bring to a boil over high heat. Reduce the heat to medium and simmer, stirring occasionally, until most of the liquid has evaporated and the vegetables are tender, about 8 minutes. Season with salt and pepper.
In a large skillet, heat the remaining 1 tablespoon of oil. Scrape the garlic off of the pork and season the slices with salt and pepper. Cook the pork over moderately high heat until browned on one side, about 4 minutes. Turn the pork over, reduce the heat to moderate and cook until white throughout, about 5 minutes longer. Spoon the vegetable pisto onto plates, top with the pork and serve.