In food processor finely chop chickpeas, mint, and garlic. Add lemon juice, salt, and eggplant. With processor running, add olive oil in a steady stream; process until smooth. Transfer to serving dish; drizzle olive oil, sprinkle fresh mint, and walnuts. Serve with grilled pita.
Brush eggplant slices with olive oil. Sprinkle with salt. Grill on uncovered grill directly over medium coals for 8 to 10 minutes or until tender, turning once. Cool slightly; process in food processor until slightly chunky.