Cut lemongrass into thin slices.
Slice chili peppers into small bits.
Crush the garlic cloves with the flat side of the knife, then mince the garlic.
Wash and cut the chicken into small bits. The bone stays in and the skin remains on in the authentic Cambodian chicken lemongrass stirfry, but you can use remove the bone and skin, or simply use boness and skinless cuts.
Heat cooking oil in the wok.
Add garlic to the wok and stir vigirously until the garil turns golden-brown (about 20 seconds).
Add lemongrass and chilies to the wok, and stir with a spatula.
Add chicken to the wok and mix well with all the other ingredients.
Add water to the wok and stir.
Add fish sauce, MSG, sugar, and oyster sauce to the wok, and stir vigorously to ensure the chicken gets well-coated with the seasonings.
Stir the contents of the wok continuously for 10 minutes as you fry, then remove from heat and serve.