Preheat oven to 200°C for the fish. Peel and slice the onion into thin wedges. Peel and mince the garlic. Halve the carrot and courgette lengthwise, then thinly slice at an angle. Trim the beans, then halve. Roughly chop the coriander leaves, discarding the stems. Slice the spring onion.
COOK THE FISH
Place the crumbed fish fillets on a lined baking tray and bake according to packet directions.
STIR-FRY VEGGIES
Heat the first measure of oil in a large deep frypan over high heat until hot. Stir-fry the onion and garlic for 2 mins, or until starting to soften. Then add the carrot and beans and stir-fry for 2-3 mins. Add the courgette and stir-fry for 2-3 mins, until all the vegetables are just tender.
COOK RICE & SAUCE
Add the rice, oyster sauce, soy sauce, the second measure of sesame oil and white pepper (if using). Cook for 2 mins, until the liquid evaporates. Add the spring onion and stir into the rice. Remove from heat.
TO SERVE
Divide the stir-fried rice between plates and top with crumbed hoki fillet. Sprinkle over the sesame seeds and drizzle with Japanese mayo.