1 Rinse fish fillets, pat dry and cut into 2 cm wide (approximately 3/4 inch) strips.
2 Rinse the chile peppers, wipe dry and cut into thin rings.
3 Mix the fish sauce and chile peppers, then spread over the fish and let stand one hour, covered.
4 Trim both ends of lemongrass and peel tough outer layer. Rinse lemongrass, pat dry and cut into 5 cm (approximately 2-inch) long pieces.
5 Rinse leek, drain and cut into thin rings. Peel ginger root and finely grate.
6 Rinse broccoli and cut into small florets, then peel the stem and cut into small pieces.
7 Heat 1 tablespoon oil in a non-stick wok. Stir-fry the broccoli, leek and lemongrass over medium heat until crisp-tender, 4-5 minutes.
8 Add ginger and stir-fry briefly. Stir in the oyster sauce and chicken stock and cook, stirring, until vegetables are coated, 2-3 minutes. Remove vegetable mixture from wok and keep warm.
9 Wipe the wok clean. Heat the remaining oil. Pat dry the fish pieces and stir-fry over medium heat until browned, 3-4 minutes.
10 Divide vegetables among warmed plates and arrange the fried fish pieces on top. Serve immediately.