Preheat a grill to medium high. Whisk the soy sauce, vinegar, 2 tablespoons each sesame oil and water and the ginger in a large bowl. Remove 1/4 cup of the dressing to a medium bowl; set aside. Whisk the five-spice powder into the large bowl and add the chicken; toss to coat and set aside to marinate, 10 minutes.
Meanwhile, brush the eggplant slices on both sides with the remaining 1 tablespoon sesame oil. Grill until well marked and tender, 3 to 4 minutes per side; transfer to a cutting board and let cool slightly. Roughly chop the eggplant and add it to the bowl with the reserved sesame dressing. Add the tomatoes, scallions and herbs; toss to coat.
Remove the chicken from the marinade, letting the excess drip off. Grill until well marked, 3 to 4 minutes, then flip and continue grilling until cooked through, about 2 more minutes. Transfer to a cutting board and let cool 5 minutes, then slice.
Serve the chicken and eggplant salad in the lettuce leaves with the eggplant salad; top with the nuts.