Prep: 1. Separate egg. 2. Cut chicken into 1 inch cubes. 3. Mince ginger and garlic. Chop scallions. Make: 1. For the sauce, combine the sugar, tomato paste, corn starch, rice vinegar, 1 tablespoon soy sauce, sesame oil and water in a small bowl. Stir until the corn starch has dissolved and no more lumps are visible. Set aside. 2. For the marinade, combine 1 tablespoon soy sauce, vinegar, egg white and flour in a large bowl. Add the chicken and mix well to coat. 3. Pour about 1-1/2 inches oil into a saucepan and set over high heat until the oil in hot. Carefully lower the chicken into the oil and fry in batches for 3 to 4 minutes or until crisp and golden. Using a slotted spoon, transfer the chicken to a plate lined with paper towels. Repeat until all the chicken is cooked. 4. Heat 2 tablespoons oil in a skillet over medium heat. When hot, toss in the chilies (if using) and stir for a few seconds, until they just start to darken in color. Turn the heat down to medium and stir in the ginger and garlic. Cook for about 30 seconds, or until fragrant. Add the sauce, stirring as it thickens. Return the chicken to the skillet and stir continuously to coat. Remove to a serving dish and scatter with scallions.