Heat ½ inch of olive oil in a large frying pan and cook the eggplant, in batches, until golden brown. Drain the cooked eggplant on paper towels. Add extra oil to the pan, as needed.

In a large, heavy-bottomed saucepan, heat ½ cup olive oil and cook the onion for 5 minutes, stirring often. Add the remaining ingredients and the drained eggplant. Combine gently but thoroughly, and simmer over low heat for 30 minutes. Taste for seasoning. The caponata should have a pleasant sweet-and-sour flavor.

Transfer the caponata to a large bowl and let cool. Serve at room temperature or cover and refrigerate overnight and serve cold.