Heat the oil in a wok over a high heat until the oil starts to shimmer. Add the ginger and stir-fry for a few seconds until fragrant.
Add the monkfish and stir-fry for 1 minute, then add the hot stock and bring to the boil. Add the shoyu sauce, rice wine, pepper and sesame oil and stir.
Add the celery and bring the mixture back to boil, then add the cornflour paste, stirring until the sauce has thickened and has turned translucent.