1 1/2 pounds eggplant (1 large), roasted

2 tablespoons olive oil

1 medium onion, chopped

2 stalks celery, from the tender inner stalks, diced

3 large garlic cloves, minced

2 red bell peppers, diced

Salt to taste

1 pound ripe tomatoes, preferably Romas, peeled, seeded and finely chopped, or 1 14-ounce can crushed tomatoes (in puree)

3 heaped tablespoons capers, rinsed and drained

3 tablespoons coarsely chopped pitted green olives

2 tablespoons sugar, plus a pinch

3 tablespoons red or white wine vinegar, or sherry vinegar (more to taste)

Freshly ground pepper to taste