Rinse the eggplants and trim off the stems. If they are large, you may need to cut them in half lengthwise.
Sprinkle the eggplants with 1 tablespoon of salt and let them sit in a colander for 30 minutes to draw out excess moisture. This will help reduce bitterness.
Rinse the eggplants thoroughly to remove the salt, then pat them dry with a clean towel.
Heat a generous amount of olive oil in a large skillet over medium heat.
Fry the eggplants in batches until they are golden brown and tender, about 4-5 minutes per side. Be sure not to overcrowd the skillet.
Transfer the fried eggplants to a paper towel-lined plate to drain excess oil.
In a bowl, mix together the chopped walnuts, minced garlic, fresh parsley, red bell pepper, olive oil, ground cumin, black pepper, salt, and red pepper flakes (if using).
Once the eggplants have cooled slightly, carefully stuff each one with the walnut mixture.
Place the stuffed eggplants in sterilized jars, packing them tightly.
In a small bowl, mix the vinegar and water. Pour this mixture over the stuffed eggplants in the jars until they are completely submerged.
Seal the jars tightly and store them in a cool, dark place for at least 2-3 weeks to allow the flavors to develop.
After the marinating period, the makdous is ready to be enjoyed. Serve as a side dish or appetizer with bread or as part of a mezze platter.
Enjoy your meal!