Preheat your oven to 375 degrees Fahrenheit.
Wash the eggplant and zucchini. Cut your eggplant in half long ways leaving the skin on. Trim the ends off your zucchini and cut them in half and then into 1/2-inch half-moons.
Peel onions and cut into one-inch dice.
Core, seed and devein the bell peppers and cut them into one-inch pieces.
Lay your vegetables out on a parchment lined sheet pan trying for a single layer with like vegetables together. drizzle with olive oil and lightly salt. Put the oiled eggplant face down once it is salted. (Use two sheet pans if necessary)
Take your garlic head and remove excess paper leaving the tight paper. Cut the top from the garlic to expose just the tips of the cloves so it is easier to squeeze out after roasting. Brush the garlic head with olive oil and nestle into the vegetables.
Roast vegetables for 30-45 minutes until they are nicely caramelized.
Add oil to a large heavy-lidded pot or dutch oven and set the pot on the stove over high heat. When the oil is hot, add your roasted vegetables to the pot with the tomato puree and paste and stir to blend. Scrape the eggplant from the skin shell and squeeze the roasted garlic from the head into the pot and stir.
Add the parsley, thyme, and capers. Season with another pinch or two of salt and black pepper to taste. Bring to a boil over high heat and once bubbling, lower the heat and simmer gently, covered, for 10 minutes.
Taste, adjust seasoning and serve warm with rice, couscous, polenta, farro or barley. This recipe is lovely with grilled or soft polenta.