Cut chicken breast fillets into very fine strips. Combine 4 tablespoons soy sauce or teriyaki marinade, roughly 4 cm fresh ginger minced (or 1-2 teaspoons ginger powder), and 1 teaspoon five-spice powder. Coat the chicken with this mixture, cover, and refrigerate for approximately 2 hours.
Heat 3 tablespoons sesame oil in a wok or large skillet over medium-high heat. Sear the marinated chicken strips, working in batches if needed, until cooked through to an internal temperature of 74°C/165°F (about 5-7 minutes). Transfer to a clean plate.
Prepare vegetables: cut 2 red peppers into small cubes, slice 2 leeks into rings, cut 1 onion into eighths, and finely mince 1 garlic clove. In the same wok over medium-high heat, sear the prepared vegetables for 2-3 minutes, stirring occasionally.
Add 600 ml broth and 1 teaspoon red curry paste to the wok, stirring well to deglaze and combine.
Return the seared chicken to the wok. Stir in 1 tablespoon freeze-dried Chinese herbs, remaining 1 teaspoon five-spice powder, and salt and pepper to taste. Simmer for 15-20 minutes until vegetables are tender.
If needed, mix 1 tablespoon cornstarch with 1 tablespoon water to form a smooth slurry, then slowly stir into the simmering sauce and cook for 2-3 minutes until thickened. Taste and season with additional soy sauce, salt, and pepper as needed.