Bring a medium pot of water to a boil. Place raisins in a small heat proof bowl and prepare an ice bath in a medium bowl.
When water is boiling, pour enough over the raisins to cover them completely. Return pot of water to a boil.
Score a shallow “x” on the bottom of each tomato. Drop in boiling water and cook for 20 seconds. Using a slotted spoon, transfer tomatoes to ice bath. When cool, peel off skin and discard, then chop flesh.
In a large pot over medium-high heat, heat olive oil until shimmering. Add eggplant in a single layer and cook, stirring frequently, until golden, 5 minutes. You may need to do this in 2 to 3 batches, depending on your pan size, adding more oil if the pan is looking dry. Using a slotted spoon, transfer eggplant to a large plate and season with salt.
Add more oil to the pot if necessary, then add peppers and sauté until mostly tender, 5 minutes; season with salt. Use slotted spoon to transfer peppers to plate with eggplant.
Add onion and celery to the pot and cover. Lower heat to medium-low and let cook, uncovering and stirring occasionally, until celery is tender, about 15 minutes.
Meanwhile, in a medium bowl or measuring cup, whisk to combine vinegar, sugar, capers, 1 teaspoon of salt, and red pepper flakes.
When celery is tender, uncover, add garlic, and cook until fragrant, 1 minute. Add chopped tomatoes, increase heat to medium, and simmer for 10 minutes more. Drain and discard liquid from golden raisins.
Return eggplant and peppers to pot along with vinegar mixture, golden raisins, olives, parsley, and pine nuts. Stir to combine and simmer, uncovered, for 10 minutes. Let cool completely before serving. (Or store in the refrigerator overnight and serve the next day.)