Salt and drain the eggplant. Place the cubed eggplant in a large colander set over a bowl or in the sink. Sprinkle with 1½ teaspoons kosher salt and toss to coat. Let sit for 30–45 minutes — the eggplant will release dark beads of moisture. Transfer the eggplant to a clean kitchen towel and pat dry firmly. This step is what gives fried eggplant its silky interior, don't skip it.

Par-blanch the celery. While the eggplant drains, bring a small saucepan of water to a boil. Add the sliced celery and blanch for 2 minutes. Drain and rinse under cold water to stop the cooking. Set aside.

Fry the eggplant. Heat ½ cup olive oil in a large heavy skillet or Dutch oven over medium-high heat until shimmering — about 3 minutes. Working in batches (don't crowd the pan), add the eggplant in a single layer and fry 4–5 minutes per batch, turning occasionally, until deeply golden on all sides and tender when pierced. Transfer each batch to a paper-towel-lined plate. Add more oil to the pan between batches if it runs dry.

Start the base. Pour off all but 3 tablespoons of oil from the pan (or wipe clean and add 3 fresh tablespoons). Reduce heat to medium. Add the diced onion and cook, stirring occasionally, for 5–6 minutes until soft and translucent but not browned. Add the garlic and cook for 30 seconds until fragrant.

Build the tomato base. Add the tomato paste and stir it into the onions for 1 minute to toast it. Add the chopped tomatoes (or crushed canned), blanched celery, ¾ teaspoon kosher salt, and a few grinds of black pepper. Stir to combine and bring to a gentle simmer. Cook for 8–10 minutes, stirring occasionally, until the tomatoes break down and the celery is tender.

Add the agrodolce. In a small bowl, whisk together the red wine vinegar and sugar until the sugar dissolves. Pour into the pan and stir. Simmer for 2 minutes to let the vinegar's sharpness cook off.

Fold in everything else. Add the fried eggplant, olives, capers, and raisins. Gently fold together — don't stir aggressively or the eggplant will break down into mush. Simmer for 5 minutes, stirring gently once or twice, until everything is coated and the flavors have started to meld. Taste and adjust — more vinegar for brightness, more sugar for sweetness, more salt if needed.

Rest. Remove from heat and let the caponata cool to room temperature. It's ready to eat now, but the flavor deepens dramatically overnight in the fridge. If you can, make it a day ahead.

Serve. Stir in the toasted pine nuts just before serving (adding them earlier turns them soggy). Spoon the caponata into a serving bowl, scatter with torn basil, and drizzle with good olive oil. Serve at room temperature with grilled or toasted crusty bread.