Chicken in Lemongrass Sauce

Name: Chicken in Lemongrass Sauce
Ingredients: 12 ounces green Chinese long beans or green beans, trimmed, cut into 1 1/2-inch pieces; 2 tablespoons peanut oil; 1 1/2 pounds skinless boneless chicken breast halves, cut crosswise into 1/2-inch-wide strips; 1 medium onion, sliced; 4 garlic cloves, minced; 1/3 cup minced lemongrass*; 3 tablespoons Thai fish sauce (nam pla)*; 3 tablespoons sugar; 2 teaspoons ground coriander; 1 teaspoon turmeric; 1/2 cup chicken stock or canned low-salt chicken broth; 2 tablespoons spicy oyster sauce*