1 pound skinless, boneless chicken breasts, cut into 1/2-inch strips
2 medium leeks, white and tender green parts only, cut into 2-inch
1 tablespoon minced fresh ginger
1 serrano chile, seeded and thinly sliced
Steamed rice, for serving
In a small bowl, whisk the stock with the fish sauce and cornstarch.
In a wok or very large skillet, heat the vegetable oil until smoking. Add the chicken and stir-fry over high heat until white but not cooked through, about 2 minutes. Using a slotted spoon, transfer the chicken to a plate. Add the leeks, ginger and chile to the wok and stir-fry over high heat until lightly browned in spots, about 2 minutes. Return the chicken and any accumulated juices to the wok and stir-fry for 1 minute. Whisk the stock mixture again, add it to the wok and simmer until the chicken is cooked through and the sauce is slightly thickened, about 1 minute longer. Serve with steamed rice.