First, cut the potatoes into long, thin strips. Toss them with cornstarch, then heat oil in a deep pan and fry the potatoes until golden brown.

Heat another pan and add 2 tablespoons of oil. Once hot, add the bell pepper, ginger, green chili, chili sauce, tomato ketchup, and soy sauce. Mix well and cook on low heat.

Dissolve 1 tablespoon of cornstarch in water and add it to the cooked mixture. Stir, then add salt and sugar. Cook for 1 to 2 minutes.

Add the fried potatoes and vinegar. Cook for 1 more minute, then add chopped cilantro and serve hot.