To prepare the eggplants: In a large bowl, combine water with the salt and rice vinegar and whisk until dissolved. Add the eggplants and soak for 10 minutes, using a heavy plate to keep them submerged. Drain, rinse, and gently squeeze out the excess moisture. Toss with the cornstarch and set aside.
To make the sauce: In a bowl, combine the soy sauce, dark soy sauce, Chinkiang vinegar, sugar, and ⅔ cup water. Whisk well and set aside.
To cook the eggplants: Heat 4 cups cooking oil in a wok over high heat to 350°F (177°C). Working in batches, carefully add the eggplants and fry for about 1 minute, until slightly golden. Remove and drain. Alternatively, steam the eggplants over boiling water for about 5 minutes, until tender.
To stir-fry the pork and aromatics: In a clean wok over high heat, add 2 tablespoons cooking oil and the ground pork. Stir-fry for about 2 minutes, until completely cooked. Add the doubanjiang, ginger, garlic, and salted chopped chilies. Stir-fry for about 1 minute, until fragrant.
To finish the dish: Pour in the prepared sauce and stir well. Add the eggplants and gently toss to combine. Mix 1 tablespoon cornstarch with 3 tablespoons water to make a slurry, stir it again, then pour it into the wok. Stir until the sauce thickens and becomes glossy. Sprinkle with scallions and serve.