Combine the fish sauce, soy sauce, oyster sauce and sugar in a small bowl
Cook the beans in the boiling water (with oil and salt) for 2 or 3 minutes until just tender, then set aside.
Slice & fry the tofu in oil & remove it from the pan.
Put more oil into the pan and fry garlic until brown. Add chicken & half of the sauce, and stir until the chicken is cooked thoroughly.
Add the sliced carrots and stir for 2min over high heat, then add the green beans, tofu and the rest of the sauce. Stir until well-combined.
Season with pepper and Serve with rice