Sprinkle 1/4 teaspoon of the salt over the eggplant, place in a colander with a plate and a 1-pound weight on top and let drain for 15 minutes.
In a large stockpot, cook the olive oil, onion, garlic, dreid porcini, oregano and red pepper flakes, stirring often on medium heat until the onions start to sizzle, about 3 minutes. Cover and reduce to a slow simmer for 5 minutes.
Pat the effplant pieces dry with a towl. Raise the heat to medium-high, uncover the stockpot and add the eggplant, stirring well for about 3 minutes. Add all of the other ingredients and bring to a boil. Reduce the heat to a slow simmer and cook, stirring every 10 minutes, for 1 hour . I find that if I place the cover on the pot and crack it open a bit for the first 25 munutes, the soup tastes a little bit better.
Place 3 cups of the soup in a blender and puree it to a smooth paste. Stir it back into the soup and simmer for 30 more minutes.
Please take a moment to thank Maria Rosa and enjoy your bowl of soup.
When you use the blender to process hot liquids, secure the top firmly in place. Hold it down with a towel and start by pulsing on and off. Open the top to release the steam, then resecure the lid and pulse your way to a cream. Be very careful of the steam which can force off the lid if not released.