In a mixing bowl, combine sliced boneless, skinless chicken with egg white, cornstarch, salt, and black pepper. Mix thoroughly until the chicken is well-coated and then let it sit for 10-15 minutes.

Heat about 1/4 inch of vegetable oil in a large skillet over medium-high heat until shimmering, about 3-4 minutes. Carefully add the marinated chicken in small batches, frying for 4-6 minutes until golden brown and crispy.

In the same skillet, reduce the heat to medium and pour in a splash of sesame oil. Add minced garlic, ginger, and dried red chilies, sautéing for 1-2 minutes until fragrant.

Stir in tomato ketchup, soy sauce, chili garlic sauce, vinegar, and sugar, mixing well. Allow the sauce to simmer for 2-3 minutes, adjusting the thickness with water if necessary.

Once the sauce is ready, gently toss the fried chicken into the skillet, coating it well with the sauce.

Remove the skillet from the heat and transfer the Spicy Dragon Chicken to a serving platter. Garnish with sliced green onions and toasted sesame seeds.