Crush or finely chop the garlic. Halve the carrot and zucchini lengthwise and thinly slice on an angle. Combine the garlic, oyster sauce, 2 tsp white vinegar, 2 tsp soy sauce and 2 tbs water in a bowl. Cut the fish into 3cm chunks and put in a large bowl. Add the cornflour and toss to coat.
Step 2 — Cook rice
Rinse the rice until the water runs clear. Put in a small saucepan with 250ml (1 cup) water, cover and bring to a simmer over medium heat. Reduce the heat to low and cook for 12 mins or until tender and the water is absorbed. Turn off the heat and stand, covered, for at least 5 mins. Fluff the rice with a fork.
Step 3 — Stir-fry veggies
Meanwhile, heat 1 tsp vegetable oil in a medium deep frypan over high heat. Stir-fry the carrot and zucchini for 2-3 mins until the vegetables are just tender. Remove from the pan.
Step 4 — Shallow-fry fish
Heat 1cm vegetable oil in the same pan over medium-high heat (see Kitchen hack). Cook the fish, turning occasionally, for 6 mins or until browned and cooked through. Remove from the pan and drain on paper towel. Season with salt and pepper. Wipe the pan clean.
Step 5 — Serve up
Return the pan to medium-high heat. Add the fish, veggies and oyster sauce mixture and stir-fry for 2 mins or until combined. Taste, then season with salt and pepper. Divide the rice and fish stir-fry among bowls. Scatter with a pinch of chilli flakes, if using, and enjoy!
Step 6 — Kitchen hack
To test if the oil is ready for frying, dip the handle of a wooden spoon into the oil. If bubbles form around the handle, the oil is hot enough.