Peel eggplants then cut them into 1/2 inch cubes and in a 10-inch skillet cook them in a 1/2 cup of oil in batches over a moderately high heat until tender and browned on all sides. About 3 to 4 minutes per batch. Transfer cooked aubergines to paper towels to drain and set aside.
Add remaining 1/4 cup oil to skillet and over moderate heat, sauté onions and garlic for 2 to 3 minutes. Add celery and cook, stirring until onion and celery are cooked but still crunchy, about 3 minutes.
Add olives and capers stirring for 2 minutes. Stir in vinegar and tomato paste and 1 tablespoons sugar.
Reduce heat and simmer, covered, stirring occasionally for 5 minutes.Salt to taste.
Add aubergines then transfer to a serving dish and serve at room temperature.
If you wish, you can garnish both the side dish and appetizer with dry toasted pine nuts.
Best prepared a day ahead and refridgerated so that all the ingredient meld together.