Toss the strips of chicken breast with the cornflour in a mixing bowl. Sprinkle with the sesame oil and toss until evenly mixed.
Heat the vegetable oil in a wok or large frypan over high heat. Stir in the chicken and cook until lightly browned, about 5 minutes. Add the garlic and cook until fragrant. Stir in the snow pea sprouts just until wilted; pour in the chicken stock and bring to a simmer. Cook and stir a few minutes until the chicken stock has thickened. Season to taste with salt and pepper.