In a large stainless steel skillet, warm half of the oil over medium-high heat.
Add half of the eggplant and cook, flipping often, until lightly browned on all sides, about 6 minutes; if the eggplant absorbs all the oil, add a generous drizzle more.
Transfer the eggplant to a paper towel lined plate; drain well.
Add the remaining ½ cup of oil and repeat with the remaining eggplant.
When you remove the second batch of eggplant, if there is not residual oil, add a couple more tablespoons to the skillet.
Add the onion and celery and sauté until they begin to caramelize, about 4 minutes.
Add the garlic and cook for an additional minute.
Add the tomatoes, reduce the flame to low, and simmer for 15 minutes, stirring often.
Add the olives, capers and ½ cup water.
Simmer for an additional 15 minutes, stirring often.
Add the eggplant and 1 cup of water.
Simmer for 15 minutes more, stirring often.
Add the red wine vinegar and simmer for 5 minutes.
Season with salt, if necessary, to taste.
Remove the caponata from the heat and cool for 30 minutes before transferring to a storage container.
Refrigerate overnight; serve cold or at room temperature.