Ingredients
Sauce
 1/2 cup water (bone broth)
 1.5 tablespoon soy sauce
 1 teaspoon sugar
 1/2 tsp vinegar
 1/4 teaspoon salt
Stir fry
1 regular eggplant (or 3 Asian long eggplants) , rolling cut
2 teaspoons cornstarch
1 Red potato, peeled, halved and sliced to 1/4-inch (1/2-cm) pieces
1 bell pepper , cut to 1 inch square
2 green onion , chopped
2 cloves of garlic , minced
3 cups  vegetable oil
1 tsp salt

Instructions
 
1. Put eggplant into a large bowl and sprinkle with 1 teaspoons salt and mix.
2. Sprinkle with 2 tsp cornstarch and gently mix, until the eggplant pieces are lightly coated.
3. Combine 1/2 cup water, 1.5 tbsp soy sauce, 1 tsp sugar, 1/2 tsp vinegar, and 1/4 tsp salt in a small bowl. Mix well and set aside.
4. Heat a deep pan with 3 cups oil over medium-high heat until hot. fry the eggplant till it light brown or soft.
5. fry the chopped potato till it gold brown
8. carefully remove the rest oil with a spoon and only leave about 1 teaspoon oil in the pan.
9. Put the pan on high temperature. Add bell pepper and green onion and garlic and stir a few times until fragrant.
10. Pour the mix sauce made in step3 into the pan. Bring it to boiling.
11. Return the eggplant and potato to the pan. Cook and stir until the sauce is evenly coated over the vegetables.
12. Turn off the temperature and transfer everything to a plate immediately.