Preheat the oven to 350° F.
Pierce the eggplant with a fork in several places.
Put it in a small roasting pan and cook for 15 minutes.
Break a whole bulb of garlic in half and add a half bulb to the roasting pan with the red pepper.
Bake the vegetables until they are very tender.
The pepper and garlic will take about 30 minutes, the eggplant 45 minutes.
To test, the pepper and eggplant should collapse when pressed with a fork.
The garlic should be tender when pierced with a paring knife.
Put the pepper in a plastic bag until it's cool enough to handle (this loosens the skin).
Peel, seed, and dice it.
Peel the garlic and eggplant.
Puree them together in a food processor or blender.
The soup can be prepared ahead to this point.
In a large saucepan, whisk together the eggplant and garlic puree, broth, olive oil, oregano, and black pepper.
Bring the soup to a boil, reduce the heat, and simmer for about 5 minutes, stirring occasionally.
Stir in the diced red pepper.
Just before serving, sprinkle each portion with croutons.
Do this at the last moment, so that they won't be mushy.