Cut eggplant with skin on into 1-inch cubes. Put eggplant on a large plate in a single layer and sprinkle lightly with salt. Set aside for 30 minutes, then rinse eggplant with water to remove salt. Squeeze to remove excess moisture.
In an extra-large, deep, cast iron or non-stick skillet, heat 2 tablespoons of the oil on medium. Add eggplant and sauté until tender. Transfer to a bowl and set aside.
In the same skillet, add remaining oil and sauté onion on medium heat for about 10 minutes.
Add green pepper, celery, and tomatoes. Cook for 15 minutes, stirring occasionally.
Add vinegar, basil, oregano, honey or agave, cayenne, walnuts or pine nuts, and cooked eggplant. Cover and simmer 5 to 8 minutes, stirring occasionally.
Mix in olives and capers.
Add salt and pepper to taste
Note: To make a smooth dip, reserve olives and capers for garnish. Transfer eggplant mixture to a blender or food processor and purée until smooth. Transfer to a bowl, cover, and chill in refrigerator for 2 hours before serving. Garnish with olives and capers.
The finished recipe can also be served hot over pasta or rice (for two).