Heat a large skillet over medium-high heat. Add the chicken and cook, breaking it up occasionally with a spoon, until nearly cooked through - about 7 minutes.

While the chicken is cooking, prepare the sauce: Whisk together the soy sauce, fish sauce, oil, water, chili paste, ginger, and garlic. Add the sauce, eggplant, and water chestnuts to the skillet with the chicken. Cook until the eggplant is soft and the chicken is cooked through.

Remove the skillet from the heat and stir in the cilantro and scallions. Serve over rice or in lettuce leaves.