Preheat the oven to 400°F.
Lightly grease a large roasting pan with olive oil and add the onions, eggplant, zucchini, fennel, celery, and bell pepper. Mix the ½ cup olive oil and the crushed garlic together then pour over the vegetables, season with salt and pepper, then toss to coat. Roast for 30 minutes, stirring twice until the vegetables are barely tender.
Meanwhile, whisk together the vinegar and tomato paste. Stir in the olives, capers, oregano, and thyme. After the initial cook time pour the vinegar mixture over the vegetables and gently stir to combine.
Continue to roast, stirring 2-3 times more, for an additional 30 minutes, until the vegetables are soft and tender.
Remove from the oven and allow the vegetables to cool in the pan to room temperature. Taste and season generously with more salt and pepper.
Serve on toasted bread as an appetizer or as part of a classic cheeseboard.
Stores in fridge for up to 10 days.