Wash and cut the eggplant into 1-inch cubes. Sprinkle salt and let it drain in a colander for about 30 minutes.

Preheat the oven to 400°F (200°C). Combine drained eggplant with bell peppers, celery, onion, and garlic in a bowl. Drizzle with olive oil and toss to coat.

Spread the vegetable mixture on a baking sheet and roast for 25-30 minutes until tender and caramelized.

Cool the roasted vegetables slightly, then combine them with diced tomatoes, capers, and olives in a bowl. Drizzle red wine vinegar and mix well.

Season with salt and pepper, cover, and let rest at room temperature for at least an hour before serving.