Step 1 Pierce the eggplants with a sharp fork in two or three places (to keep them from exploding) and place them as high as you can on a V-rack roaster. Set over a medium-low gas flame or over hot coals and grill, turning about three times, 15 minutes to a side, or until completely soft and the skin is black and blistery, about 45 minutes total. The longer and slower the grilling, the creamier the eggplant will be. When the eggplants collapse, remove from the grill and let cool slightly. Remove the black parched skin, then squeeze gently to remove any juices. Discard the juices, and crush the pulp to a purée with a fork.
Step 2 Meanwhile, grill the pepper. Remove the pepper when soft, cover with a sheet of plastic and allow to cool. Core, seed and slip off the skin. Chop fine and mix with the eggplant.
Step 3Mash the garlic to a paste with half the walnuts and the salt in a mortar and pestle or food processor. Add the cheese, oil, vinegar, and salt and pepper, and pulse to combine.
Step 4In a serving bowl, combine the garlic-walnut mixture with the eggplant-pepper pulp and mix well. Correct the seasoning. Mix the parsley and remaining walnuts and sprinkle on top. Serve with pita toasted until crisp. May be stored, covered, in the refrigerator for several days.