Defrost and clean the sea cucumber, cut into large pieces and blanche with ginger and green onion, set aside;
Bring the chicken broth to a boil, turn off the heat and immediately soak the blanched sea cucumber into the broth, set aside;
Defrost and clean the tiger prawns, then peel and devein the prawns, marinate with chicken powder and corn starch, set aside;
Cut the leeks into sections, finely chop the garlic and ginger, set aside;
Heat the wok, add some oil, stir fry the garlic, ginger and leeks, then add the chicken broth, oyster sauce and water to cook for 5 minutes; add the sea cucumber and cook until the sauce thickens, ready to present on a plate;
Heat the wok, add some oil and cook the tiger prawns until done, put them onto the sea cucumber and ready to serve.