Place eggplant in colander, and sprinkle generously with salt. Let stand 10 minutes. Rinse under cold water, and pat dry with paper towels.
Heat oil in large pot or Dutch oven over medium heat. Add onion,and garlic, and sauté 10 minutes, or until onion is softened and translucent. Add eggplant and mushrooms, and sauté 10 minutes more, or until vegetables are tender.
Stir in tomatoes, 1 cup water, wine, capers and oregano. Bring to a boil, cover, reduce heat to low, and simmer 50 to 60 minutes, or until vegetables are tender. Season with salt and pepper.