Slice the eggplant about 1/2-inch thick. Brush both sides lightly with oil, sprinkle with salt and pepper, and arrange on a preheated grill rack or pan. Grill until browned, then turn them over, brush with more oil then cook until tender, about 8 to 10 minutes total. Remove from the grill and cut each slice into quarters.
In a large serving bowl, toss the eggplant, lentils, tomatoes, onions, and cilantro. Mix all the dressing ingredients in a jar and shake well, then toss in the salad. Allow to rest at room temperature about 10 to 15 minutes, then serve.