Combine all the ingredients for the sauce. Season the monkfish and prawns with salt and pepper.
Heat the oil in a wok over a high heat until the oil starts to shimmer. Add the fish and prawns and cook for 2 minutes, carefully turning the fish occasionally, then tip in the ginger, carrots, sugar snaps and spring onions.
Fry for 30 seconds, then add the sauce and bring to the boil. Turn down the heat and simmer for 2–3 minutes until the vegetables are just tender and the fish is cooked through. Serve immediately.